This easy peanut butter cake is made in one bowl with kitchen staples. It’s quick to whip up and so peanut buttery and delicious!
Are you ready for your new favorite cake? (Assuming you like peanut butter. If not I’ll see you back here for a non-pb recipe in a few days.)
But if you’re a peanut butter fanatic like me then you’ll go cah-razy for this easy peanut butter cake. Soft cake (made with a doctored cake mix) gets topped with the most amazing creamy peanut butter frosting.
And the result is a dessert that no one can resist.
Why you’ll love this easy peanut butter cake:
- The ingredients are all kitchen staples you probably have on hand now
- You don’t need a stand mixer or other special equipment
- It keeps well so you can make it a day ahead
How to make the cake
- Combine the cake ingredients in a large bowl
- Beat with an electric mixer until smooth
- Pour into a baking dish
Then you’ll bake for about half an hour and that’s it! Totally do-able even if you don’t bake often.
Cool your cake completely before you make the frosting.
- I used a yellow cake mix here but you can use white cake mix if you prefer it.
How to make the frosting
- Heat milk, peanut butter, and butter in a saucepan until melted
- Remove from the heat and stir in powdered sugar, vanilla, and salt
- Pour over the cake
Top with peanuts if you want, then chill until the frosting is set, about half an hour. Then serve!
- After you add the powdered sugar, the frosting will still be somewhat thin compared to a buttercream; that’s fine! It will set up quite a bit in the fridge, but never get as firm as a buttercream would. It stays really creamy.
- I topped my cake with roasted salted peanuts but Reese’s pieces, chopped peanut butter cups, or chopped Butterfingers would be delicious too.
How to store your cake
After you’ve frosted your peanut butter cake, it can be stored, covered, in the fridge for a couple of days.
You can also freeze slices of your cake (tightly wrapped) for two months.
Unfrosted cake can be stored, covered, at room temperature for a day or so.
Can I use natural peanut butter in this cake?
I don’t recommend it, especially in the frosting. You want to use a processed peanut butter that doesn’t separate to ensure you’re not getting too much oil in your cake/frosting.
I always use Jif when I bake because it’s my favorite to eat, but use whatever brand you like (that isn’t natural, of course).
Can I make this as a layer cake or cupcakes?
The cake can definitely be baked in two 8-inch round cake pans. (I don’t recommend 9-inch cake pans because they layers will be very thin). Start checking your layers after about 25 minutes; they’ll probably take longer but it’s better to check sooner than to let them over-bake.
You can also bake the cake in about 24 to 28 muffin cups. Start checking cupcakes for done-ness after about 18 minutes.
I don’t recommend using the frosting for a layer cake or cupcakes though. I’d recommend a peanut butter buttercream instead.
Did you make this easy peanut butter cake? Great! Let me know what you think with a comment and a rating below. Then post a pic on IG–tag @theitsybitsykitchen so I can see your delicious creations!
This easy peanut butter cake starts with a cake mix to make it quick and simple. It's topped with creamy peanut butter frosting, making it totally irresistable!
- Peanut Butter Cake
- 1 15.25-ounce box yellow cake mix*
- 1 1/4 cups water
- 1/2 cup creamy peanut butter don’t use natural
- 1/3 cup vegetable oil
- 4 large eggs
- 1 teaspoon vanilla extract
- Peanut Butter Frosting
- 2/3 cup creamy peanut butter don’t use natural
- 1/2 cup unsalted butter
- 1/2 cup whole milk
- 3 1/2 cups powdered sugar
- 1/2 teaspoon vanilla
- 1/4 teaspoon salt
- salted peanuts coarsely chopped for serving (if desired)
- Preheat the oven to 350 degrees. Spray a 13- by 9-inch baking dish with cooking spray and set aside.
- Combine the cake ingredients in a large mixing bowl and beat with an electric mixer on medium for about 2 minutes, until batter is smooth. Scrape down the sides and bottom of the bowl and beat a few seconds more.
- Pour the batter into the prepared baking dish and bake 30 to 35 minutes, until a cake tester inserted into the center of the cake comes out clean.
- Cool completely on a wire rack before frosting.
- Combine the peanut butter, butter, and milk, in a medium saucepan set over medium heat. Heat mixture, stirring often, until the butter and peanut butter are melted and the mixture is smooth.
- Remove from the heat and add the powdered sugar, vanilla, and salt. Stir vigorously until smooth; it should be fairly thick but still pourable. (The frosting will set up quite a bit in the fridge.)
- Pour over the cooled cake, smooth the top, and sprinkle with chopped peanuts (if desired).
- Refrigerate to set the frosting, 20 to 30 minutes, then slice and serve.
- Store cake in the fridge, covered, for up to 2 days or in the freezer, tightly wrapped, for up to 2 months.
- *I used Betty Crocker Super Moist yellow cake mix. You can use white cake mix if you prefer.
- Before frosting your cake, you can store it at room temperature (covered) for about a day.
- If you prefer, you can top your cake with Reese’s Pieces or chopped Butterfingers or peanut butter cups.
- If you want to bake this cake as either cupcakes or cake layers, see the body of this post for tips.