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Chocolate Peanut Butter Sheet Cake

Chocolate Peanut Butter Sheet Cake

A moist 9x13 inch chocolate cake topped with whipped peanut butter frosting, chocolate drizzle, peanut butter cups, and chopped peanuts.
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Prep Time 1 hour 25 minutes
Cook Time 35 minutes
Total Time 2 hours
Course Dessert
Cuisine American
Servings 20 slices
Calories 485 kcal

Equipment

  • 9x13 inch metal baking pan
  • Parchment paper
  • Large mixing bowl
  • Whisk
  • Electric mixer
  • Offset spatula

Ingredients
  

Main Ingredients

  • 1 ¾ cup all-purpose flour for the cake
  • ¾ cup unsweetened cocoa powder for the cake
  • 1 ½ tsp baking powder for the cake
  • 1 ½ tsp baking soda for the cake
  • 2 cup granulated sugar for the cake
  • 1 tsp kosher salt for the cake
  • 2 large eggs for the cake
  • 1 cup milk for the cake
  • ½ cup vegetable oil for the cake
  • 2 tsp vanilla extract for the cake
  • 2 tsp instant coffee powder optional, for the cake
  • 1 cup boiling water for the cake
  • 1 cup unsalted butter 2 sticks, softened, for the frosting
  • 4 cup powdered sugar sifted, for the frosting
  • ½ cup smooth peanut butter for the frosting
  • ¼ tsp kosher salt for the frosting
  • 1 tbsp milk for the frosting
  • ½ cup semi-sweet chocolate chips for the topping
  • 2 tbsp heavy cream for the topping
  • 3 tbsp smooth peanut butter warmed, for the topping
  • 4 oz mini peanut butter cups halved, for the topping
  • ¼ cup salted peanuts finely chopped, for the topping

Instructions
 

Cooking

  • Prep the pan. Heat the oven to 350 degrees F. Grease a 9x13 inch metal pan and line it with parchment paper with an overhang.
  • Mix the batter. Whisk the flour, cocoa, baking powder, baking soda, sugar, and salt. Add the eggs, milk, oil, vanilla, and coffee powder, then whisk in the boiling water until smooth. The batter will be thin.
  • Bake. Pour into the pan and bake 30 to 35 minutes until a toothpick in the center comes out clean. Cool completely, about 1 hour.
  • Make the frosting. Beat the butter 3 minutes until fluffy, gradually beat in the powdered sugar, then add the peanut butter, salt, and milk until light and spreadable.
  • Frost. Spread the frosting evenly over the cooled cake.
  • Top. Melt the chocolate chips with the cream in 20 second bursts and drizzle over the cake, followed by the warmed peanut butter. Finish with the peanut butter cups and peanuts.

Notes

Substitutions: Natural cocoa works in place of Dutch processed. Leave out the coffee if you prefer.
Tips: Cool the cake fully before frosting and sift the powdered sugar.
Storage: Room temperature 3 days, refrigerator 5 days, freezer up to 3 months.
Keyword Celebration Cake, Chocolate Cake, chocolate peanut butter sheet cake, Dessert for a Crowd, Party Cake, Peanut Butter Cake