Peanut Butter Sheet Cake
By National Peanut Board
Ingredients
Cake
- ½ cup peanut butter
- 1 cup water
- 2 sticks (1 cup) unsalted butter
- 2 cups all-purpose flour
- 2 cups granulated sugar
- 1 teaspoon salt
- 1 teaspoon baking soda
- 2 large eggs
- ½ cup milk
Frosting
- 1 stick (½ cup) unsalted butter
- ½ cup peanut butter
- 6 tablespoons milk
- 1 teaspoon vanilla extract
- 4 cups powdered sugar
Directions
Prepare the Cake
- Preheat the oven to 350°F. Grease a sheet cake pan and set aside.
- Combine the dry ingredients. In a large mixing bowl, whisk together the flour, sugar, salt, and baking soda.
- Prepare the peanut butter mixture. In a saucepan over medium heat, combine the peanut butter, water, and butter. Bring the mixture to a rapid boil.
- Combine the mixtures. Carefully pour the hot peanut butter mixture over the dry ingredients. Stir until well combined.
- Add the remaining ingredients. Add the eggs and milk, mixing until the batter is smooth and evenly combined.
- Bake. Pour the batter into the prepared sheet cake pan and spread evenly. Bake for 20–25 minutes, or until the cake is set and a toothpick inserted into the center comes out clean.
Prepare the Frosting
- In a saucepan over low heat, combine the butter, peanut butter, and milk. Stir gently until the butter melts and the ingredients begin to blend together. Do not bring the mixture to a boil.
- Add the vanilla extract and powdered sugar while keeping the saucepan over low heat.
- Continue stirring until all the ingredients are fully incorporated and the frosting is smooth.
- Remove from the heat and immediately spread the hot frosting over the cake.
Finish the Cake
- Spread the frosting over the cake while the frosting is still hot.
- Allow the cake to cool completely and let the frosting set.
- Cut into 24 squares and serve.
Cooling & Storage
- Cooling: Allow the frosted cake to cool completely before covering or storing. This prevents condensation from forming and keeps the frosting from becoming sticky.
- Room temperature: Store tightly covered at room temperature for up to 3 days.
- Refrigerator: For longer storage, cover tightly and refrigerate for up to 5 days. Allow individual pieces to come to room temperature before serving for the best texture.
- Freezing: For longer-term storage, wrap individual pieces tightly in plastic wrap and place in a freezer-safe container or bag. Freeze for up to 2 months. Thaw overnight in the refrigerator or at room temperature before serving.
