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Easy Peanut Butter Cake

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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!

sliced peanut butter cake on a piece of parchment paper

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

how to make peanut butter 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.

Note:

  • I used a yellow cake mix here but you can use white cake mix if you prefer it.

How to make the frosting

how to make easy peanut butter 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! 

Notes:

  • 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.

A few more recipes you might like:
White Chocolate Peanut Butter Balls
3-Ingredient Peanut Butter Fudge
Praline Cake
Peanut Butter Cupcakes

slice of peanut butter cake on a plate with a fork taking a bite out of it
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!

5 from 13 votes
sliced peanut butter cake on a piece of parchment paper
Print
Easy Peanut Butter Cake
Prep Time
20 mins
Cook Time
30 mins
Cooling Time
3 hrs
Total Time
50 mins
 

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!

Course: Dessert
Cuisine: American
Servings: 14
Author: Kelsie
Ingredients
  • 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)
Instructions
  1. Cake
  2. Preheat the oven to 350 degrees. Spray a 13- by 9-inch baking dish with cooking spray and set aside.
  3. 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.
  4. 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.
  5. Cool completely on a wire rack before frosting.
  6. Frosting
  7. 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.
  8. 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.)
  9. Pour over the cooled cake, smooth the top, and sprinkle with chopped peanuts (if desired).
  10. Refrigerate to set the frosting, 20 to 30 minutes, then slice and serve.
  11. Store cake in the fridge, covered, for up to 2 days or in the freezer, tightly wrapped, for up to 2 months.
Recipe Notes
  • *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.

Comments

  1. Rita Kay says

    5 stars
    I just made this cake for the second time. This time I used Pillsbury golden butter cake mix. This is the best cake I have ever tasted. My new favorite cake. Again, thanks for sharing this recipe.

    Reply

  5. Laura says

    5 stars
    Kelsie – you know how I love peanut butter! And absolutely cannot resist peanut butter cake! This looks and sounds so inviting. And that frosting….Swooning!

    Reply

  9. Cheyanne says

    5 stars
    Eeeeee! I am definitely a peanut butter fanatic, so I totally need this cake in my life!!! Not only does it look and sound absolutely delicious, but I love how easy-peasy it is to make!! It’s almost dessert time here and I’m thinking I need to whip this together pronto! Pinned!

    Reply

  13. Leanne says

    5 stars
    Ummm, you pretty much had me at peanut butter! And then you go ahead and make the cake easy too. Now I must make it. Or at least that frosting! I could totally eat that with a spoon!

    Reply

  14. Milena says

    I may need to double the frosting just to be able to enjoy some as a dip while waiting for the first batch to set on top of the cake:) Sounds delicious!

    Reply

  15. David @ Spiced says

    5 stars
    Peanut butter cakes are the cat’s meow…if cat’s liked peanut butter, that is. Wait. Do cat’s actually like peanut butter? I know dogs do. So maybe this cake is like a dog’s woof. A Cookie woof. So there we have it. This peanut butter cake is a Cookie’s woof. 🙂

    Reply

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