Peanut Butter Sheet Cake Recipe

A piece of peanut butter cake on a plate.

Course: Cake, Dessert

Cuisine: American

Prep Time: 30

Cook Time: 27

Total Time: 57

Servings: slices

Calories: 522kcal

Author: Becky Hardin

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

Print Recipe

US Customary - Metric

Equipment

Kitchen Scale (optional)
Baking Sheet (make sure it has a rim!)
Hand Mixer

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

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.
In a small saucepan set over medium heat, bring the water, unsalted butter, and vegetable oil to a boil. Remove from heat.
1 cup water, ½ cup unsalted butter, 2 tablespoons vegetable oil
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.
¾ cup creamy peanut butter
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.
26.5 ounces yellow cake mix
In a separate small bowl, whisk the buttermilk, eggs, and vanilla together.
½ cup buttermilk, 2 large eggs, 2 teaspoons pure vanilla extract
Pour the buttermilk mixture into the rest of the cake batter. Stir with a spatula until well combined.
Pour the batter onto the prepared sheet cake pan and use a spatula to evenly distribute the cake batter in the pan.
Bake in the preheated oven for 27-28 minutes, or until a toothpick inserted in the middle comes out clean.
Remove cake from oven and let cool completely before frosting.
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.
1½ cups unsalted butter, 1½ cups creamy peanut butter, 3 tablespoons heavy cream, 1 tablespoon pure vanilla extract, 5 cups powdered sugar
Smooth an even layer of frosting over the top of the cake and decorate as desired.
peanut butter cups

Notes

I don't recommend using natural peanut butter in this recipe. The oils will separate, resulting in a not very pleasant cake.
For a bit more texture in your cake, you can use chunky peanut butter, or fold in chopped peanuts!
You can make this cake with all different kinds of nut and seed butters, like almond butter, Nutella, cashew butter, or sunflower seed butter! Get creative!
Remove the saucepan from the heat before adding the peanut butter to prevent scorching.
To turn this recipe into a layer cake, you can simply cut out layers from the sheet cake pan, or pour the batter into 2 or 3 round cake pans. They can be 9-inch or 8-inch round pans, but be sure to only fill them about halfway. Bake for about 30-35 minutes.
Nutritional information does not include optional decorations.

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.

Nutrition