Peanut Butter Sheet Cake
A moist and flavorful peanut butter cake baked in a jelly roll pan, with a silky-smooth peanut butter frosting.
Ingredients
For the Cake
- 2 1/2 cups all-purpose flour
- 1 teaspoon baking soda
- 1 teaspoon salt
- 1/2 teaspoon cinnamon
- 1/2 cup unsalted butter, at room temperature
- 3/4 cup smooth peanut butter
- 1 cup granulated sugar
- 3/4 cup brown sugar
- 2 large eggs, at room temperature
- 1 teaspoon vanilla extract
- 1 cup buttermilk, at room temperature
- 1/4 cup water
For the Frosting
- 3/4 cup unsalted butter, softened
- 1 cup peanut butter
- 1 teaspoon vanilla extract
- 1/4 teaspoon salt
- 2 cups powdered sugar, measured then sifted
- 2 tablespoons heavy whipping cream
Instructions
For the Cake
- Preheat the oven to 350 degrees F. Spray a standard size jelly roll pan (half sheet pan) with nonstick spray and set aside.
- In a medium-size mixing bowl, whisk together the flour, baking soda, salt and cinnamon. Set aside.
- In the bowl of a stand mixer fitted with the paddle attachment, or using a hand mixer, beat the butter and peanut butter until smooth.
- With the mixer on medium-high speed, add the granulated sugar and brown sugar and mix until smooth, about 2 minutes.
- Add the eggs and vanilla. Beat on medium-high speed for another 2 minutes or so. Mixture should be smooth, slightly fluffy, and lighter in color.
- With the mixer on low, alternately add the flour mixture and the buttermilk, starting and ending with the flour. Stir in the water.
- Pour the batter into the prepared pan and spread to ensure the cake batter is evenly distributed in the pan.
- Bake for about 20 to 25 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs on it. The top of the cake won't be shiny anymore and should have a little bounce back when you touch the top of it.
- Remove the cake from the oven and place the pan on a cooling rack to cool.
For the Frosting
- In a medium size mixing bowl, beat together the softened butter and peanut butter until smooth.
- Stir in the vanilla and salt.
- Gradually add the powdered sugar, followed by the heavy cream.
- Turn the mixer to medium-high and beat until smooth and fluffy, about 2 minutes.
- When the cake is cooled completely, cover the cake with the peanut butter frosting.