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+ servings
sliced peanut butter cake on a piece of parchment paper

Easy Peanut Butter Cake

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
Prep Time 20 minutes
Cook Time 30 minutes
Cooling Time 3 hours
Total Time 50 minutes
Servings 14
Author Kelsie


  • 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)


  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.