This old-fashioned peanut butter cake is one of those classic homemade cake recipes everyone loves! It’s full of peanut flavor, and the rich frosting tastes a little bit like the filling of a peanut butter cup!
This peanut butter cake is a delicious, easy-to-make treat. It’s not one of those fancy layer cakes that requires careful stacking and frosting—nope! It’s made in a 9×13 pan, so once it’s done baking, all you have to do is spread on the peanut butter frosting with a spatula, then slice the peanut butter sheet cake into squares.
I told you it was easy!
Peanut Butter Cake from Scratch
This homemade peanut butter cake is the perfect combination of two favorites: cake and peanut butter. The rich, creamy peanut butter is baked directly into the cake layer and in the frosting too, creating a dense yet moist treat that is sure to please peanut butter lovers.
And because peanut butter is such a versatile flavor, there are endless flavor combinations that can be used to create your own personalized peanut butter cake:
- Love peanut butter and jelly? Use strawberry frosting!
- Want a traditional chocolate and peanut butter combo? Top the cake with mini chocolate chips or peanut butter cups, or swap the peanut butter frosting for homemade chocolate frosting.
- Cream cheese frosting (or peanut butter cream cheese frosting!) are delicious too.
- For an upscale touch, sprinkle crunchy sea salt flakes over the top of the cake.
However you make it, this peanut butter cake is definitely going to be a crowd-pleaser. In fact, you should probably make enough for everyone to have seconds!
See recipe card below this post for ingredient quantities and full instructions.
For the Cake:
- All-purpose flour
- Granulated sugar
- Baking soda
- Whole milk – I recommend using whole milk for the best cake texture.
- Eggs – Here’s the best way to crack eggs.
- Vanilla extract
- Unsalted butter
- Peanut butter – Use creamy peanut butter for a smooth texture, or crunchy peanut butter if you want bits of peanut in your cake.
For the Frosting:
- Unsalted butter – Let the butter soften to room temperature.
- Peanut butter
- Whole milk
- Powdered sugar – Also known as confectioners’ sugar.
How to Make Peanut Butter Cake
Preheat your oven to 350ºF, then butter and lightly flour a 9×13 cake pan. Tap out the excess flour.
2. Start the Cake Batter
Whisk the flour, sugar, and baking soda in the large bowl of an electric mixer. Add the milk, eggs, and vanilla to the dry ingredients (flour mixture), and beat on medium-low speed until the mixture is well-combined.
3. Make the Peanut Butter Mixture
In a small saucepan set over medium heat, combine the water, butter, and peanut butter. Cook, stirring often, until the butter and peanut butter melt and the mixture becomes creamy and smooth.
4. Finish the Batter
Pour the peanut butter mixture into the rest of the batter. Beat on medium speed to combine for about 2 minutes.
Pour the batter into the prepared baking pan and bake for 35 to 40 minutes, or until a toothpick comes out clean. Let the cake cool completely before adding the frosting.
6. Make the Frosting
Cream the butter and peanut butter using an electric mixer fitted with a paddle attachment. Slowly pour in the sugar and continue to beat until the sugar is completely mixed into the butters. Beat in the milk if you need to thin the frosting out.
7. Frost the Cake
Use a spatula to spread the frosting over the top of the peanut butter cake.
How to Store Peanut Butter Cake
To ensure that your cake stays fresh and delicious, it’s important to store it properly. For best results, wrap the cake in plastic wrap or aluminum foil (or transfer leftovers to an airtight container) and store it in the refrigerator for up to four days. Let it sit at room temperature for a few minutes before serving.
If you need to store the cake for longer than that, it can be frozen for up to three months. When you’re ready to enjoy it, simply thaw the cake overnight in the refrigerator before serving.
Peanut butter is made up of two main ingredients: peanuts and oil. Over time, the oil in the peanut butter will start to separate from the nuts, making the peanut butter runny. Many brands of peanut butter contain an emulsifier, which helps to keep the oil and nuts mixed together, but most natural peanut butter brands do not, and these are the ones that are likely to separately and get runny. If this happens, simply stir the peanut butter until the oil is evenly distributed.
Peanut butter cake is a type of cake that is made with peanut butter. Sometimes it’s made with yellow cake mix, but this peanut butter cake recipe is from scratch! Some peanut butter cake recipes have chocolate frosting, but it’s also common to use peanut butter frosting for double the peanut butter flavor!
Yes, peanut butter can go bad, but it takes a while. Peanut butter is made with natural oils that will eventually go rancid, but it takes a long time or improper storage conditions for this to happen. You’ll know your peanut butter has gone bad if it changes color or texture, or if it develops a strange odor.
The first step is to make the cake batter; you’ll need to gather the ingredients listed in the recipe card below, then follow the instructions for making the cake. When the cake is done baking, you’ll let it cool to room temperature before adding the homemade peanut butter frosting. Because this is a simple 9×13 cake recipe, it’s a great cake for beginning bakers—there’s no layering, assembly, or piping frosting required!
More Recipes for Peanut Butter Lovers
- Peanut Butter Kiss Cookies
- Peanut Butter Lasagna
- Chocolate Peanut Butter Pie
- Peanut Butter & Banana Oatmeal Bars
Peanut Butter Cake
- 2 cups all-purpose flour
- 2 cups granulated sugar
- 1 tsp baking soda
- ½ cup whole milk
- 2 large eggs
- 1 tsp vanilla extract
- 1 cup water
- ½ cup unsalted butter
- ¾ cup peanut butter
- ½ cup unsalted butter softened
- 1 cup peanut butter
- ⅓ cup whole milk
- 3 cups powdered sugar
- Preheat the oven to 350F. Butter and lightly flour a 9×13 baking dish.
- Add the flour, sugar, and baking soda to the bowl of an electric mixer.
- On medium-low speed, add milk, eggs, and vanilla and beat until well combined.
- In a small saucepan over medium heat, add water, butter, and peanut butter and cook until creamy and well blended, stirring frequently.
- Add to the rest of the batter and mix on medium speed to combine, about 2 minutes. Pour the batter into the prepared baking dish.
- Bake for 35-40 minutes or until a cake tester comes out clean. Cool cake to room temperature.
- For the frosting, cream together the butter and peanut butter in an electric mixer with a paddle attachment. Slowly add the sugar and beat until all sugar is gone. Thin with the milk, if needed, to reach the desired consistency.
- Using a spatula, spread frosting over the cooled cake.