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Chocolate Peanut Butter Sheet Pan Cake

This sheet pan cake combines rich chocolate flavors and creamy peanut butter in a moist, tender dessert that's perfect for gatherings.
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Prep Time 20 minutes
Cook Time 35 minutes
Total Time 55 minutes
Servings: 16 slices
Course: Dessert, Snack
Cuisine: American
Calories: 350
Ingredients Method Notes

Ingredients
  

For the Cake
  • 1.5 cups all-purpose flour
  • 1 cup sugar
  • 0.5 cups unsweetened cocoa powder
  • 1 tsp baking soda
  • 0.5 tsp baking powder
  • 0.25 tsp salt
  • 1 cup buttermilk
  • 0.5 cups vegetable oil
  • 2 large eggs
  • 2 tsp vanilla extract
  • 1 cup boiling water
For the Frosting and Ganache
  • 1 cup semi-sweet chocolate chips
  • 1 cup creamy peanut butter
  • 2 cups powdered sugar
  • 0.5 cups butter, softened
  • 1 tsp vanilla extract (for the buttercream)
  • 0.5 cups heavy cream (for ganache)

Method
 

Preparation
  1. Preheat your oven to 350°F (175°C) and grease a sheet pan to prevent sticking.
  2. In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt until well combined.
  3. In another bowl, blend the buttermilk, vegetable oil, eggs, and 2 tsp vanilla extract until smooth and evenly mixed.
  4. Pour the wet ingredients into the dry mixture, gently mixing until just combined.
  5. Carefully stir in the boiling water until the batter is smooth and evenly mixed — it will be quite thin.
  6. Pour the batter into the prepared sheet pan, spreading it out evenly.
Baking
  1. Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
Ganache and Frosting
  1. For the ganache, heat the heavy cream in a saucepan until it just starts to simmer. Pour the hot cream over the chocolate chips in a bowl and let it sit for a few minutes before stirring until smooth and glossy.
  2. To prepare the buttercream, beat together the creamy peanut butter and softened butter until smooth. Gradually add in the powdered sugar and mix until creamy and fluffy.
Final Assembly
  1. Once the cake has cooled completely, spread the peanut butter buttercream evenly over the top, then drizzle with the chocolate ganache to make it shine.
  2. Slice into squares and serve — enjoy the joyful reactions from your family and friends!

Notes

Make sure to incorporate the boiling water slowly to avoid splashing, and remember that it helps to create a moist cake. Allow the cake to cool completely before frosting to prevent the buttercream from melting. Use a serrated knife to slice the cake for clean, tidy edges. For an added touch, sprinkle some chopped peanuts on top of the ganache for crunch. If you want to prep ahead, you can bake the cake a day before and frost it shortly before serving.