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Peanut Butter Sheet Cake with Fluffy Peanut Butter Frosting

A moist, nutty peanut butter sheet cake topped with fluffy peanut butter frosting and crushed peanuts.
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Prep Time 20 minutes
Cook Time 35 minutes
Total Time 55 minutes
Servings: 12 servings
Course: Dessert
Cuisine: American
Calories: 360
Ingredients Equipment Method Notes

Ingredients
  

Cake
  • 2 cups all-purpose flour
  • 2 tsp baking powder
  • 0.5 tsp baking soda
  • 0.5 tsp salt
  • 0.5 cup unsalted butter softened
  • 1 cup creamy peanut butter
  • 1.5 cups brown sugar packed
  • 2 eggs large
  • 1 tsp vanilla extract
  • 1 cup milk
Frosting
  • 1 cup unsalted butter softened
  • 1 cup creamy peanut butter
  • 3 cups powdered sugar sifted
  • 0.25 cup milk add more if needed for consistency
  • 1 tsp vanilla extract
  • crushed peanuts optional garnish

Equipment

  • Mixing bowls
  • 9x13-inch baking pan
  • Wire rack
  • Hand mixer or stand mixer

Method
 

  1. Preheat oven to 350°F (175°C). Grease a 9x13-inch pan or line with parchment paper.
  2. Whisk flour, baking powder, baking soda, and salt in a medium bowl.
  3. Beat butter, peanut butter, and brown sugar until creamy. Add eggs one at a time, then vanilla.
  4. Alternately add dry ingredients and milk to the peanut butter mixture until smooth.
  5. Pour batter into pan and smooth top. Bake 30–35 minutes until a toothpick comes out clean. Cool completely.
  6. Beat butter and peanut butter until fluffy. Gradually add powdered sugar, vanilla, and milk to reach desired consistency.
  7. Spread frosting evenly over cooled cake and sprinkle crushed peanuts on top.
  8. Slice and serve. Store leftovers in an airtight container.

Notes

You can make this cake a day ahead. Optional: drizzle with melted chocolate for variation.