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Peanut Butter Sheet Cake
4.6 from 549 votes

Peanut Butter Sheet Cake

Peanut Butter Sheet Cake features a moist peanut butter–infused cake baked on a sheet pan, topped with a rich peanut butter frosting that sets while warm. The cake combines both granulated and brown sugar for depth, with buttermilk enhancing tenderness. The frosting blends butter, peanut butter, and buttermilk for a creamy topping poured warm over the cake, creating a melt-in-the-mouth finish suitable for casual gatherings or dessert plates.

Prep Time
15 mins
Cook Time
15 mins
Total Time
30 mins
Servings: 16 servings
Course: Dessert, Cake, Others
Cuisine: American

Ingredients

Cake:
  • 1/4 /4 cup peanut butter creamy
  • 1 cup water
  • 1/2 /2 cup butter
  • 1 cup sugar
  • 1 cup brown sugar
  • 2 cups flour
  • 1 teaspoon salt
  • 1 teaspoon baking soda
  • 2 egg
  • 1/2 /2 cup buttermilk see note for easy substitution
  • 1 teaspoon vanilla
Frosting:
  • 3/4 /4 cup butter
  • 6 Tablespoons buttermilk
  • 1/2 /2 cup peanut butter
  • 3 1/2 /2 cups powdered sugar
  • 1 Tablespoon vanilla

Instructions

    Cup of Yum
  1. Preheat oven to 375 degrees.
For the cake:
  1. In a medium pot add the peanut butter, water, and butter and bring to a boil. Remove from heat.
  2. In a separate bowl, mix together the sugar, brown sugar, flour, salt, and baking soda with a fork. Mix together with the peanut butter mixture.
  3. Add the eggs, buttermilk, and vanilla to the bowl and mix well.
  4. Stir well and pour into greased or parchment lined cookie sheet pan with a little edge (12X17 jellyroll pan). Bake for 13-15 minutes at 375 degrees. Do not overbake!
For the Frosting:
  1. In a small pot bring the butter, buttermilk, and peanut butter to a boil. Remove pan from the heat and add the powdered sugar and vanilla. Pour frosting over the warm cake.

Notes

  • Substitute buttermilk by mixing 1 tablespoon lemon juice or white vinegar with milk to equal 1 cup; let stand 5 minutes before use.
  • Do not overbake the cake; baking 13–15 minutes ensures moist texture.

Nutrition Information

Serving 1grams

Nutrition Facts

Serving: 16 servings

Amount Per Serving

Calories

% Daily Value*

Serving 1grams

* Percent Daily Values are based on a 2,000 calorie diet.