This peanut butter sheet cake with peanut butter frosting is a moist, fudgy peanut butter cake topped with a sweet peanut butter frosting. Perfect for any type of gathering, where you can cut the slices into any size you need!
This peanut butter sheet cake has become a new obsession at our house. The cake is so soft and has the perfect subtle peanut butter flavor, and the peanut butter frosting is next level! I can't stop dreaming of the endless possibilities of ways I can use it. So if you're a peanut butter lover you're going to fall in love with this cake.
For more peanut butter recipes, try my: peanut butter s'more cookies, my peanut butter pie with chocolate ganache, or my puppy chow cookies.
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Why You Will Love This Cake
- Peanut Butter Flavor: Loads of peanut butter flavor in both the cake and the icing.
- Sheet Cake: I love a simple sheet cake that is easy to make and cut for serving a crowd.
- Easy: This cake is an easy one to make and doesn't require a mixer and can be baked and served in less than an hour!
Ingredient Notes
Full ingredient measurements and instructions can be found in the recipe card below.
- Butter: I like to use salted butter, but unsalted is great too.
- Sugars: You will use both granulated and brown sugar in this cake.
- Peanut Butter: I have not tested this cake using a "natural" peanut butter. Those tend to be wetter and more oily, so I don't know how the cake would turn out.
- Eggs: Make sure your eggs are room temperature before mixing into the batter.
- Buttermilk: I always try and use a full fat buttermilk if I can find it because it will help the cake be more moist.
Step by Step Instructions
- Step 1: Add butter and water to a small saucepan over medium heat. Bring mixture to a boil, remove from heat and mix in peanut butter until completely melted in.
- Step 2: In a large bowl whisk together the sugar, brown sugar, flour, baking soda and salt. Pour melted butter/peanut butter over the dry ingredients while they are still warm. Whisk together until all combined.
- Step 3: In a measuring cup or small bowl whisk the eggs, buttermilk and vanilla. Mix into the cake batter.
- Step 4: Pour batter into prepared pan. Bake for 17-22 minutes, or until edges are pulling away. When there is about 5 minutes left before the cake is done baking, start the peanut butter frosting.
- Step 5: Add butter, peanut butter and milk to the same small saucepan and bring to a boil over medium heat. Remove from heat and pour into a medium mixing bowl with vanilla, salt and powdered sugar. I like to mix with electric beaters on low to make sure it's smooth. You do not want to start the frosting too soon or it will start to thicken and harden and you want that to happen on top of the cake.
- Step 6: Pour frosting over cake after it's cooled for 3-5 minutes, and use a spatula to spread evenly over the cake. The cake needs to be warm enough that the frosting can spread easily over the cake.
Expert Baking Tips
- This peanut butter frosting would also be great topped on brownies, or on top of my chocolate buttermilk texas sheet cake.
- I love topping this cake with chopped peanuts and flaked salt, but it would also be so good with chopped up peanut butter cups or chocolate shavings.
- Cakes will have the best results if made with room temperature ingredients. I like to pull my eggs, buttermilk and butter out of the fridge an hour or two before I start baking.
FAQ
If you don't have buttermilk on hand you can make your own by adding 2 teaspoons of vinegar to your ½ cup of milk and allow it to sit a few minutes to curdle.
Yes, you can half this recipe (click .5 version) and bake it in a 9x13 pan.
Yes! This cake is excellent subbing in a gluten free 1:1 flour.
Storing & Freezing
This peanut butter sheet cake can be stored at room temperature in an airtight container for 3-4 days while remaining fresh. You can also store it in the fridge if you prefer to serve it cold.
This cake freezes well for up to 3 months. Cut into slices and store in a tupperware. When ready to serve, thaw and allow to come to room temperature again.
Other Popular Recipes to Try
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Peanut Butter Sheet Cake
Ingredients
Peanut Butter Cake
- 1 cup (227 g) salted butter
- 1 cup (236.59 ml) water
- ½ cup (129 g) creamy peanut butter
- 1½ cups (300 g) granulated sugar
- ½ cup (110 g) brown sugar
- 2 cups (280 g) all-purpose flour
- 1 teaspoon baking soda
- 1 teaspoon salt
- 2 large eggs room temperature
- ½ cup (120 g) buttermilk room temperature
- 1 teaspoon vanilla extract
Peanut Butter Frosting
- ½ cup (113.5 g) salted butter
- ½ cup (120 g) milk
- ½ cup (129 g) peanut butter
- 1 teaspoon vanilla
- ¼ teaspoon (0.25 teaspoon) salt
- 4 cups (480 g) powdered sugar
- ¼ cup (36.5 g) chopped peanuts for topping
- flaked salt for topping
Instructions
- Preheat oven to 350 F and grease a cookie sheet pan (13×18''). Set aside.
- Add butter and water to a small saucepan over medium heat. Bring mixture to a boil, remove from heat and mix in peanut butter until completely melted in.
- In a large bowl whisk together the sugar, brown sugar, flour, baking soda and salt. Pour melted butter/peanut butter over the dry ingredients while they are still warm. Whisk together until all combined.
- In a measuring cup or small bowl whisk the eggs, buttermilk and vanilla. Mix into the cake batter.
- Pour batter into prepared pan. Bake for 17-22 minutes, or until edges are pulling away. When there is about 5 minutes left before the cake is done baking, start the peanut butter frosting.
- Add butter, peanut butter and milk to the same small saucepan and bring to a boil over medium heat. Remove from heat and pour into a medium mixing bowl with vanilla, salt and powdered sugar. I like to mix with electric beaters on low to make sure it's smooth. You do not want to start the frosting too soon or it will start to thicken and harden and you want that to happen on top of the cake.
- Pour frosting over cake after it's cooled for 3-5 minutes, and use a spatula to spread evenly over the cake. The cake needs to be warm enough that the frosting can spread easily over the cake. Top with chopped peanuts and flaked salt.
Sandy
I love sheet pan cakes and bars and this is no exception! It’s moist, flavorful and the frosting is also fantastic! So good!
Bailey
Truly delicious!! Will definitely be making again!
Lauren S
Just made this! Couldn’t wait for it to cool to taste….yum!
Mary Ann Cameron
Can i make this in a 9x13 pan? Would i just do half the recipe?
Brooke Homec
Yes, halving it will be perfect!
Marie
Can't wait to try this recipe! Love my peanut butter....
Kelsje
Made this for a company pot luck and got raving reviews!
Amanda
This was seriously soooo delicious!! Now that I’ve tasted this, I crave it sometimes. My son has requested it for his birthday cake coming up.
My question is, can this be made in regular cake pans? Will it rise like a normal cake or is there anything I’d need to change to make sure it does? I’m thinking it would probably be enough for two cake pans maybe? Please let me know, otherwise I’ll just have to experiment with it and possible make it multiple times and that would just be terrible! 😜
Brooke Homec
Honestly I haven't tried, but my inclination is it wouldn't rise correctly baked thick. If you try it let me know! Or maybe I just need to make a different pb cake that's thick!
Amanda
I’ll give it a try. If it doesn’t work out, I suppose I can just do thin layers to stack up. Then I’ll be forced to eat the scraps I cut off. Yum.
It would be great if you came out with a peanut butter cake! I’d want it to taste exactly like the sheet cake. It is perfection!!!
Amanda
I successfully baked this as a layered cake for my kid’s birthday party with only a couple adjustments: I added 1 tsp baking powder and baked in two 8” cake pans for about 35 minutes. I used the frosting in between layers as well as on the outside. It was delicious!