Peanut Butter Sheet Cake Recipe in Just 7 Steps

Published: 18 May 2026

Here is a short video explaining the process, scroll down for detailed ingredients and step by step recipe method. Thanks for coming and do not forget to check other recipes on our homepage.

Table of Contents

Ingredients for Peanut Butter Sheet Cake (with Exact Amounts)

Getting the ingredients right before you start is the single most important step in baking. This recipe is straightforward and relies on pantry staples you likely already have at home. That said, a few specific choices — especially the type of peanut butter — will make or break your cake, so read through this section before you head to the store.

For the Cake

The cake itself is built on a simple base of flour, sugar, and peanut butter, brought together with butter, oil, and buttermilk for a texture that is soft, moist, and just slightly dense in the most satisfying way. Here is exactly what you will need:

2 cups (250 g) all-purpose flour
1 cup (200 g) granulated white sugar
¾ cup (150 g) light brown sugar, packed
¾ tsp baking soda (not baking powder — they are different and not interchangeable)
¾ tsp fine salt
¾ cup (170 g) unsalted butter
½ cup (128 g) creamy peanut butter (regular store-bought, not natural)
1 cup (240 ml) water
¼ cup (60 ml) neutral oil (canola, vegetable, or avocado oil all work)
2 large eggs, at room temperature
½ cup (120 ml) full-fat buttermilk
1½ tsp pure vanilla extract

For the Peanut Butter Frosting

The frosting is made entirely on the stovetop and poured directly onto the warm cake, where it sets into a glossy, fudgy layer that is completely irresistible. It uses just a handful of ingredients but delivers enormous flavor. Here is what you need:

½ cup (113 g) unsalted butter
½ cup (128 g) creamy peanut butter (again, regular — not natural)
⅓ cup (80 ml) whole milk or buttermilk
3 cups (360 g) powdered sugar, sifted to remove lumps
1 tsp pure vanilla extract
Pinch of fine salt

Optional Toppings

Once the frosting is poured and slightly set, you can add toppings for extra texture, flavor, and visual appeal. Chopped salted roasted peanuts are the classic choice and add a satisfying crunch that contrasts beautifully with the soft cake and creamy frosting. Halved or chopped Reese’s Peanut Butter Cups pressed gently into the frosting before it fully sets is always a crowd-pleaser. Mini chocolate chips scattered over the top melt slightly into the warm frosting and give every bite a peanut-butter-chocolate combo. A drizzle of melted dark chocolate or a simple ganache makes the cake look bakery-worthy with almost no extra effort.

A Few Important Notes on Ingredients

The type of peanut butter you use matters more in this recipe than almost any other ingredient. Regular creamy peanut butter — the kind like Jif, Skippy, or any store brand that does not separate — is what you need here. Natural peanut butter, where the oil floats to the top and needs stirring, has a much thinner, oilier texture that does not behave the same way in baking. Multiple bakers have tested this and reported greasy cakes and broken frostings when using natural peanut butter. It is simply not worth the risk — save the natural stuff for your toast. Unsalted butter is preferred here because peanut butter already brings a fair amount of salt on its own, so using unsalted butter keeps the flavor balanced and under your control. If you only have salted butter, that is fine — just reduce the added salt in the recipe by half. Finally, if you do not have buttermilk, you can make a quick substitute: pour one tablespoon of lemon juice or white vinegar into a measuring cup, then fill it to the ½ cup line with regular whole milk. Stir it once and let it sit for five minutes before using it in the recipe — it works perfectly.

Step-by-Step Recipe Method

This is the heart of the post, so take your time reading through all the steps before you start. The process is genuinely simple, but a few moments — like frosting the cake quickly before it sets — require your full attention. Read everything once, gather your equipment, measure out your ingredients, and then start. You will be glad you did.

Step 1: Get Your Oven and Pan Ready

Start by preheating your oven to 350°F (175°C). Give it a full 15 minutes to come up to the right temperature before you put anything in — a properly preheated oven is the difference between a cake that rises evenly and one that bakes unevenly or sinks in the middle. While the oven is heating, prepare your pan. Take a 9×13-inch baking pan and grease it thoroughly with butter or non-stick cooking spray, making sure to get into all the corners and up the sides. You can also line the bottom with a sheet of parchment paper for even easier removal, though it is not strictly necessary. Set the pan aside and move on to the batter.

Step 2: Combine the Dry Ingredients

In a large mixing bowl — the biggest one you have, because you will be adding everything else to this bowl later — whisk together the all-purpose flour, granulated sugar, brown sugar, baking soda, and salt. Use a proper wire whisk and give it a good 30 seconds of stirring to make sure everything is evenly distributed. The brown sugar can sometimes have small clumps from moisture, so break those up with your fingers or the back of a spoon before whisking. Getting these dry ingredients fully mixed before adding anything wet means the leavening is spread evenly throughout the batter, which helps the cake rise consistently from edge to center. Set this bowl aside on the counter within easy reach.

Step 3: Heat the Peanut Butter Mixture

Place a medium saucepan on the stove over medium heat. Add the butter, peanut butter, oil, and water to the pan. Stir the mixture gently with a wooden spoon or heatproof spatula as everything begins to melt together. You want to cook this until the butter is completely melted and the peanut butter is fully incorporated into a smooth, liquid mixture — this takes about four to five minutes over medium heat. Keep stirring occasionally so nothing sits on the bottom and burns. Once the mixture comes to a gentle, rolling boil — you will see bubbles breaking across the surface — remove the pan from the heat immediately. Do not let it boil for more than a few seconds. Overboiling can scorch the butter and give the cake a bitter, slightly burned undertone that you cannot fix after the fact.

Step 4: Mix the Wet and Dry Ingredients Together

Pour the hot peanut butter mixture directly into the bowl with your dry ingredients. Use a spatula or wooden spoon to stir everything together until just combined. The batter will look a little rough at first, but keep stirring gently and it will smooth out within a minute or so. In a separate small bowl or large measuring cup, whisk together the two eggs, the buttermilk, and the vanilla extract until the mixture is smooth and uniform. Pour this egg mixture into the peanut butter batter and stir again until everything is fully incorporated. The finished batter will be noticeably thin — almost runny — and that is completely normal and expected. A thin batter is what gives this cake its wonderfully moist, tender crumb. Do not be tempted to add more flour; trust the recipe.

Step 5: Pour and Bake

Pour the batter into your prepared 9×13 pan. Because the batter is thin, it will spread easily on its own, but use a spatula to gently guide it into the corners and make sure the surface is level. Place the pan in the center rack of your preheated oven. Bake for 25 to 30 minutes, checking for doneness at the 25-minute mark. To test, insert a toothpick or a thin skewer into the very center of the cake. When you pull it out, you want to see just a few moist crumbs clinging to it — not wet batter, but not completely clean either. A few crumbs means the cake is perfectly cooked and will be moist all the way through. A completely clean toothpick is actually a sign that you have gone slightly too far, so err on the side of pulling it out a minute earlier rather than later. The cake will continue cooking for a minute or two from residual heat once you remove it from the oven.

Step 6: Make the Frosting

Start making the frosting about 15 to 20 minutes after the cake comes out of the oven — you want the cake to be warm but not scorching hot when you frost it, and you want the frosting ready to go the moment it is finished. Place a medium saucepan on the stove over medium heat and add the butter, peanut butter, and milk. Stir the mixture constantly as everything melts and comes together. Once it is smooth and fully combined, bring it just to a boil, then immediately remove the pan from the heat. Stir in the sifted powdered sugar, vanilla extract, and a pinch of salt. Whisk or stir vigorously until the frosting is completely smooth with no lumps remaining. It should look glossy and pourable — similar to a thick syrup or a thin chocolate sauce. If it looks too thick to pour, stir in a tablespoon of milk at a time until it loosens up. If it seems too thin, add a little more sifted powdered sugar and stir until it thickens.

Step 7: Frost the Cake and Let It Set

This step requires you to move with some confidence because the frosting starts setting the moment it begins to cool. Have the cake pan ready and waiting on a flat, heat-safe surface. Pour the warm frosting over the top of the warm cake in an even stream, starting in the center and working your way out toward the edges. Use an offset spatula or the back of a large spoon to spread it quickly and evenly all the way to the corners. If you are adding toppings like chopped peanuts, Reese’s cups, or chocolate chips, scatter them over the frosting right now — within the first minute or two while the frosting is still soft enough for them to stick. Once the frosting is on, leave the cake alone and let it set at room temperature for at least 30 minutes before cutting into it. The frosting will firm up from glossy and liquid to a slightly matte, fudge-like finish. When you are ready to serve, cut it directly in the pan with a sharp knife, wiping the blade clean between cuts for neat slices.

Storing the Cake

This cake stays fresh and delicious at room temperature for up to three days — just cover the pan tightly with plastic wrap or aluminum foil, or transfer slices to an airtight container. If you want to keep it longer, store it in the refrigerator for up to a week, where the frosting becomes firmer and almost fudge-like in texture, which many people actually prefer. For long-term storage, you can freeze the cake unfrosted — wrap it tightly in two layers of plastic wrap followed by a layer of foil and freeze for up to three months. When you are ready to use it, thaw it overnight at room temperature and make fresh frosting to pour over the top.

Variations in the Recipe

Once you have made this cake once, you will start dreaming up ways to make it your own. The base recipe is incredibly versatile, and even small changes can take it in a completely different direction. Here are the best variations — all tested, all delicious.

Chocolate Peanut Butter Sheet Cake

This is the most popular variation, and honestly, it is hard to argue with the logic — chocolate and peanut butter are one of the great flavor combinations in the entire dessert world. There are a few ways to go about it. The simplest is to fold half a cup of semi-sweet chocolate chips directly into the batter before pouring it into the pan. They distribute throughout the cake as it bakes and create little pockets of melted chocolate in every slice. For a more dramatic chocolate presence, drizzle a simple ganache over the set peanut butter frosting — just melt equal parts heavy cream and chopped dark chocolate together, let it cool slightly, and pour it over in zigzag lines. If you want to go all the way, you can skip the peanut butter frosting entirely and use a chocolate fudge frosting instead, then top the finished cake with chopped Reese’s Peanut Butter Cups. Either way, you end up with something extraordinary.

Peanut Butter and Jelly Sheet Cake

This variation is nostalgic in the best possible way — it takes the classic peanut butter and jelly sandwich and turns it into a full-sized sheet cake. After you pour the batter into the pan, drop heaping spoonfuls of your favorite jam or jelly across the surface — strawberry, grape, and raspberry all work beautifully. Then use a butter knife or a skewer to swirl the jam through the batter in long, looping strokes. The jam bakes right into the cake, creating sweet, fruity ribbons woven through the peanut butter crumb. Keep the frosting as written — the peanut butter frosting plays perfectly against the jam — and you end up with a cake that tastes like childhood but feels completely grown-up.

Crunchy Peanut Butter Sheet Cake

If you are someone who likes texture in your desserts, this simple swap makes a big difference. Replace the creamy peanut butter in both the cake batter and the frosting with crunchy peanut butter. The little bits of peanut throughout the cake give each bite a satisfying crunch that contrasts nicely with the soft crumb. Finish the frosted cake with a generous handful of chopped salted roasted peanuts scattered over the top while the frosting is still wet. The saltiness of the peanuts cuts through the sweetness of the frosting in a way that makes you keep going back for just one more slice.

Peanut Butter Banana Sheet Cake

This one is especially good when you have very ripe bananas sitting on your counter that are past the point of eating fresh. Replace half a cup of the milk and half a cup of the granulated sugar in the batter with one cup of thoroughly mashed ripe bananas. Stir the banana into the batter along with the eggs and vanilla, and it blends in seamlessly. The banana adds natural sweetness and moisture, and it deepens the flavor of the peanut butter in a way that is completely harmonious. Keep the peanut butter frosting on top, and if you want to make it look beautiful, arrange a row of fresh banana slices down the center of the frosted cake just before serving.

Coffee-Spiked Frosting

This variation does not change the cake at all — just the frosting — but it makes a surprisingly big difference. Add one to one-and-a-half tablespoons of instant espresso powder to the frosting mixture when you stir in the powdered sugar. The coffee does not make the frosting taste like coffee — instead, it deepens and intensifies the peanut butter flavor, cuts through some of the sweetness, and adds a subtle complexity that makes the whole cake taste more sophisticated. It is one of those additions that people cannot quite put their finger on but always notice. If you are serving this to adults, consider trying it at least once.

Less-Sweet Glaze Option

Not everyone wants a thick, fudgy layer of frosting on their cake, and that is completely valid. If you prefer a lighter finish, halve the frosting recipe and add an extra two tablespoons of milk to thin it out into a glaze consistency. Pour it over the warm cake in a thin, even stream and let it run into the surface of the cake slightly before setting. The result is a lightly glazed cake that is far less sweet but still has that essential peanut butter flavor in every bite. It also makes the cake a little easier to eat in large quantities, which is exactly what you want at a party.

Mistakes to Avoid

Even a simple recipe like this has a few places where things can go wrong. These are the most common mistakes home bakers make with peanut butter sheet cake, and knowing about them ahead of time means you can avoid every single one of them.

Using Natural Peanut Butter

This is the single most common mistake, and it causes the most dramatic failures. Natural peanut butter — the kind where the ingredients list reads only “peanuts and salt” and the oil floats to the top of the jar — behaves completely differently from regular commercial peanut butter when heated and baked. It is much thinner and oilier, and when it goes into the cake batter, it makes the whole thing greasy and heavy. When it goes into the frosting, the oil tends to separate as it cools, leaving you with a broken, oily glaze instead of a smooth, glossy finish. Brands like Jif, Skippy, or any store-brand equivalent with added stabilizers are what you want here. Save the natural peanut butter for smoothies and salad dressings.

Overbaking the Cake

A dry, crumbly peanut butter sheet cake is almost always the result of leaving it in the oven just a few minutes too long. The tricky thing is that the top of the cake can look perfectly done — or even slightly underdone — while the edges and bottom are already past their prime. Always start checking the cake at the 25-minute mark using the toothpick test, and remember that a few moist crumbs on the toothpick is the goal. The cake keeps cooking from residual heat for a minute or two after it leaves the oven, so pulling it out when it looks just barely done means it will be perfectly moist by the time it actually cools. Do not wait for the toothpick to come out completely clean.

Waiting Too Long to Frost the Cake

The peanut butter frosting sets quickly — that is actually one of its best qualities, because it firms up into that fudge-like finish that everyone loves. But it means you cannot make the frosting and then walk away to do something else before coming back to frost the cake. Once you take the frosting off the heat, you have a very short window — maybe two or three minutes — to get it onto the cake before it becomes too thick to spread properly. Have your cake already cooling on the counter, have your spatula ready, and pour the frosting immediately after it comes off the stove. If it does start to stiffen in the saucepan before you can get it on the cake, put the pan back over low heat for 30 seconds and stir until it loosens again.

Overmixing the Batter

This is a mistake that affects almost every type of cake, and peanut butter sheet cake is no exception. Once you combine the wet and dry ingredients, gluten starts developing in the flour — and the more you stir, the more gluten develops, and the tougher and chewier the cake becomes. Stir the batter just until there are no more visible streaks of dry flour. A few tiny lumps are completely fine and will disappear during baking. The batter should look smooth and uniform but should not be stirred beyond that point. Step away from the bowl.

Overheating the Peanut Butter Mixture

When you are heating the butter, peanut butter, oil, and water together on the stove, the goal is to melt everything into a smooth, hot liquid — not to cook it. As soon as the mixture reaches a boil, remove it from the heat. If you leave it on the burner past that point, the butter can start to brown, the peanut butter can develop a slightly bitter flavor, and the whole mixture can turn from a smooth liquid into something grainy or separated. Medium heat is the right temperature for this step — high heat gets things moving too fast and is harder to control. Stay at the stove and watch it closely; this step only takes about four to five minutes.

Using Stale Baking Soda

Baking soda is the only leavening agent in this recipe, and if it has lost its potency, the cake will come out flat, dense, and heavy. Baking soda loses effectiveness over time, especially if the box has been sitting open in a humid kitchen. A quick test: drop half a teaspoon into a small cup of hot water. If it fizzes actively and immediately, it is still good. If it just sits there with little to no reaction, it is time for a new box. It is a small thing, but using fresh baking soda is the difference between a cake that rises beautifully and one that stays flat and dense no matter how carefully you followed everything else.

Wrong Pan Size

The recipe is calibrated for a 9×13-inch baking pan. If you use a smaller pan, the batter will be too deep and will take significantly longer to bake through — by which point the edges and top will be overdone before the center is set. Using a pan that is too large will give you a cake that is too thin, dries out faster, and overbakes quickly. If you only have a 15×10-inch jelly roll pan, you can use it — the cake will be thinner, and you should start checking for doneness around the 18 to 20-minute mark rather than the 25-minute mark.

Conclusion

Peanut butter sheet cake is one of those recipes that earns a permanent spot in your baking rotation after the first time you make it. It is simple enough for a beginner but delivers results that feel well above beginner level — a soft, moist cake with rich peanut butter flavor and a fudgy frosting that people will genuinely rave about. The fact that it all comes together in one pan, with no mixer required, and is ready from start to finish in under an hour just makes it even better. Whether you make it exactly as written or use one of the variations to put your own spin on it, this cake is going to be a hit every single time. Go make it this weekend. You will not regret it.

FAQs

Can I make peanut butter sheet cake ahead of time?

Yes, and it actually works beautifully as a make-ahead dessert. You can bake the cake a full day ahead of time, cover the pan tightly with plastic wrap or foil once it has cooled completely, and store it at room temperature overnight. When you are ready to serve it, make the frosting fresh and pour it over the cake — fresh warm frosting always looks and tastes better than day-old frosting that has been sitting around. If you want to get even further ahead, you can freeze the unfrosted cake for up to three months wrapped tightly in plastic wrap and foil. Thaw it overnight at room temperature, then frost and serve as usual.

Does peanut butter sheet cake need to be refrigerated?

It does not have to be refrigerated, and at room temperature it stays moist and delicious for up to three days stored in an airtight container or covered tightly with plastic wrap. That said, refrigerating the cake is a completely valid choice — it keeps for up to a week in the fridge, and the frosting takes on an even firmer, denser, fudgier texture when cold that a lot of people love. If you refrigerate it, let individual slices sit at room temperature for about ten minutes before eating to let the frosting soften slightly.

Why did my cake turn out dry?

Dry cake almost always means one of three things: the cake was overbaked, the flour was over-measured, or the buttermilk was skipped or substituted with a lower-fat milk. For baking, the toothpick test with a few moist crumbs as the target is the most reliable way to avoid overbaking. For measuring flour, the best practice is to spoon the flour into your measuring cup and level it off with a knife — scooping the cup directly into the flour bag packs in far more flour than the recipe intends, which dries out the finished cake. And always use full-fat buttermilk or a proper buttermilk substitute — it is the moisture and tenderness workhorse in this recipe.

Can I use a boxed cake mix instead of making it from scratch?

You can, and it is a perfectly reasonable shortcut when you are short on time. Replace the flour and both sugars in the cake batter with two boxes of yellow cake mix and use three large eggs instead of two. Keep everything else — the peanut butter, butter, oil, water, buttermilk, and vanilla — the same as written. The cake will be slightly less nuanced in flavor compared to the scratch version, but it will still be moist, peanut-buttery, and very well received. The frosting is still made from scratch and makes the whole thing taste homemade regardless.

Can I make this cake gluten-free?

Yes. Replace the all-purpose flour with a high-quality 1-to-1 gluten-free baking flour blend — the kind that already contains xanthan gum. Add one extra teaspoon of baking powder alongside the baking soda to help with the rise, since gluten-free flours can be slightly heavier. Everything else in the recipe stays exactly the same. Multiple readers who have made this substitution report results that are nearly identical in texture and flavor to the original. Just make sure your peanut butter and any toppings you use are also certified gluten-free if you are baking for someone with celiac disease.

My frosting hardened before I could spread it — what do I do?

This happens when the frosting cools too much before it gets onto the cake, which is an easy fix. Put the saucepan back on the stove over very low heat and stir the frosting gently until it loosens up and becomes pourable again — this usually only takes a minute or two. Add a tablespoon of milk if it seems too thick even after warming. Next time, make sure the cake is ready and waiting before you start the frosting, and move quickly the moment the frosting is finished. Having your spatula in hand and the cake right in front of you before you even turn on the burner makes the whole process much smoother.

Can I use crunchy peanut butter instead of creamy?

Absolutely. Crunchy peanut butter works in both the cake batter and the frosting and adds a nice textural contrast throughout. The small pieces of peanut in the frosting give it a slightly more rustic look, which a lot of people find charming. Just make sure you are using a regular commercial crunchy peanut butter, not a natural variety — the same rule applies whether you are using creamy or crunchy. If you go crunchy, finishing the cake with chopped salted peanuts on top doubles down on the texture and makes the whole thing even better.

Latest Posts

Please Write Your Comments

Comments (0)

Write a comment

INSTRUCTIONS:

Be Respectful
Stay Relevant
Stay Positive
True Feedback
Encourage Discussion
Avoid Spamming
No Fake News
Don't Copy-Paste
No Personal Attacks

`