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Peanut Butter Sheet Cake Recipe

This peanut butter sheet cake with peanut butter frosting is for all my peanut butter lovers-- double the peanut butter, double the fun!

Prep Time
30 mins
Cook Time
30 mins
Total Time
57 mins
Servings: 24 slices
Calories: 522 kcal
Course: Dessert , Cake
Cuisine: American

Ingredients

For the Cake
  • 1 cup water
  • ½ cup unsalted butter cut into large cubes (1 stick)
  • 2 tablespoons vegetable oil
  • ¾ cup creamy peanut butter
  • 26.5 ounces yellow cake mix (2 (13.25-ounce boxes)
  • ½ cup buttermilk room temperature
  • 2 large eggs room temperature
  • 2 teaspoons pure vanilla extract
For the Frosting
  • 1½ cups unsalted butter slightly melted (3 sticks)
  • 1½ cups creamy peanut butter
  • 3 tablespoons heavy cream (35% fat)
  • 1 tablespoon pure vanilla extract
  • 5 cups powdered sugar
  • peanut butter cups optional, for decoration

Instructions

    Cup of Yum
  1. Preheat oven to 350°F. Line a 13x18-inch rimmed baking sheet with parchment paper (leave parchment paper slighter higher than the sides of the pan so it’s easier to lift the cake out after). Lightly spray parchment paper with nonstick spray then set aside.
  2. In a small saucepan set over medium heat, bring the water, unsalted butter, and vegetable oil to a boil. Remove from heat.
  3. Stir the creamy peanut butter into the saucepan until it’s melted and well combined with the rest of the butter mixture. Be sure that the saucepan is no longer over the stove heat for this step or the peanut butter will start to burn.
  4. Pour this wet mixture into the cake mix and fold (by hand with a spatula; don’t use an electric mixer) until the wet ingredients are fully mixed with the dry ingredients. Let cool for 5 minutes before the next step.
  5. In a separate small bowl, whisk the buttermilk, eggs, and vanilla together.
  6. Pour the buttermilk mixture into the rest of the cake batter. Stir with a spatula until well combined.
  7. Pour the batter onto the prepared sheet cake pan and use a spatula to evenly distribute the cake batter in the pan.
  8. Bake in the preheated oven for 27-28 minutes, or until a toothpick inserted in the middle comes out clean.
  9. Remove cake from oven and let cool completely before frosting.
  10. While the cake cools, make the frosting: In a large bowl, using a hand mixer, beat the butter, peanut butter, heavy cream, and vanilla until smooth, about 1 minute. Beat in the powdered sugar slowly until fully mixed in, then beat on high until light and fluffy, about 5 minutes. If the frosting seems too thick, beat in an additional tablespoon of heavy cream.
  11. Smooth an even layer of frosting over the top of the cake and decorate as desired.

Notes

  • Storage: Store peanut butter sheet cake in an airtight container at room temperature for up to 3 days, in the refrigerator for up to 5 days, or in the freezer for up to 3 months.
  • Nutritional information does not include optional decorations.

Nutrition Information

Serving 1slice Calories 522kcal (26%) Carbohydrates 56g (19%) Protein 8g (16%) Fat 31g (48%) Saturated Fat 14g (70%) Polyunsaturated Fat 4g Monounsaturated Fat 11g Trans Fat 1g Cholesterol 59mg (20%) Sodium 336mg (14%) Potassium 176mg (5%) Fiber 2g (8%) Sugar 41g (82%) Vitamin A 531IU (11%) Vitamin C 0.01mg (0%) Calcium 95mg (10%) Iron 1mg (6%)

Nutrition Facts

Serving: 24slices

Amount Per Serving

Calories 522

% Daily Value*

Serving 1slice
Calories 522kcal 26%
Carbohydrates 56g 19%
Protein 8g 16%
Fat 31g 48%
Saturated Fat 14g 70%
Polyunsaturated Fat 4g 24%
Monounsaturated Fat 11g 55%
Trans Fat 1g 50%
Cholesterol 59mg 20%
Sodium 336mg 14%
Potassium 176mg 4%
Fiber 2g 8%
Sugar 41g 82%
Vitamin A 531IU 11%
Vitamin C 0.01mg 0%
Calcium 95mg 10%
Iron 1mg 6%

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