Peanut Butter Sheet Cake with Peanut Butter Frosting
This Peanut Butter Sheet Cake recipe starts with a cake mix and tastes like a moist peanut butter brownie, topped with Peanut Butter Frosting and chopped peanuts. The easy icing is made in the microwave and has a fudgy texture without all the work! No electric mixer required!
Servings: 16 servings
Calories: 1sixteenth
Ingredients
- ½ cup salted butter, cut into 4 pieces 1 stick
- ⅔ cup creamy peanut butter
- ⅓ cup milk From whole to skim
- ⅓ cup vegetable oil
- 1 teaspoon vanilla extract
- 2 large eggs
- 1 box yellow cake mix or Golden Butter I used Duncan Hines
- ⅓ cup chopped peanuts to sprinkle on frosting
Peanut Butter Frosting
- ½ cup salted butter, cut into 4 pieces
- ½ cup creamy or crunchy peanut butter
- ⅓ cup milk From whole to skim
- 1 teaspoon vanilla extract
- 1 16 ounce box powdered sugar (3 ¾ cups)
Instructions
- Preheat oven to 350F degrees. Lightly grease a 15x10-inch sheet pan or 13x9-inch baking pan. Baking times included for both below.
- Combine butter, peanut butter, and milk in a large microwave-safe bowl. Microwave on HIGH (1100 watts), uncovered, for 1 minute. Stir together until the butter is melted and peanut butter mixture is smooth. Stir in oil and vanilla.
- Add eggs and lightly beat with a spoon or whisk in the center of the batter. Then, incorporate them into the rest of the batter by stirring well.
- Add the cake mix and stir vigorously with a spoon or whisk until no cake mix lumps are visible, about 45 strokes.
- Spoon the peanut butter batter in the prepared baking pan, then spread the batter to the edges of the pan.
- To bake in a 15x10 inch sheet pan, bake for 13 to 15 minutes or until a toothpick inserted in the center almost comes out clean. Do not over bake.
- To bake in a 13x9 inch baking pan, bake for 19 to 21 minutes or until a toothpick inserted in the center almost comes out clean.
- Once done, let it cool in pan 15 minutes before spreading the frosting over it and sprinkling with peanuts.
- For the best slicing, let stand at room temperature one hour before cutting for icing to set up. Or, refrigerate for 30 minutes to get nice clean slices.
Prepare Peanut Butter Frosting (Icing)
- Combine butter, peanut butter, and milk in a large microwave-safe bowl. Microwave on HIGH (1100 watts), uncovered, for 50 seconds. Stir together until the butter is melted.
- Stir in vanilla and powdered sugar. Stir well until smooth. Frosting should be pourable but thick enough to spread.
- When cake has cooled 15 minutes, pour the frosting (icing) over the cake and spread to the edges of the pan.
- Sprinkle with chopped peanuts.
Notes
If you prepare the frosting ahead of time and it has become too firm to pour, simply microwave it for 20 to 30 seconds and stir. It will loosen up quickly.
How to make Peanut Butter Frosting in a Saucepan: Combine same amounts of butter, peanut butter, and milk in a large saucepan. Heat over medium heat, stirring often, until melted and smooth. Remove from heat. Stir in vanilla and powdered sugar. Stir well until smooth. Frosting should be almost pourable but thick enough to spread. Spread the peanut butter frosting over the slightly warm cake.
Crunchy peanut butter can also be used in the frosting in place of sprinkling with chopped peanuts.
