A moist, rich, and indulgent peanut butter sheet cake topped with creamy peanut butter frosting. Perfect for any peanut butter lover!

1 1/2 cups all-purpose flour

1 1/2 teaspoons baking powder

1/4 teaspoon salt

1/2 cup unsalted butter, softened

1 cup creamy peanut butter

1 cup granulated sugar

1/2 cup brown sugar, packed

2 large eggs

1 teaspoon vanilla extract

1/2 cup whole milk

For the frosting:

1/2 cup unsalted butter, softened

1 cup creamy peanut butter

4 cups powdered sugar

1/4 cup whole milk

1 teaspoon vanilla extract

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Preheat the oven to 350°F (175°C). Grease and flour a 9x13-inch baking dish.
In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
In a large bowl, beat the butter and peanut butter together until smooth and creamy. Add the granulated sugar and brown sugar, and beat until fluffy.
Beat in the eggs one at a time, then add the vanilla extract.
Gradually add the dry ingredients to the wet ingredients, alternating with the milk, beginning and ending with the dry ingredients. Mix until just combined.
Pour the batter into the prepared baking dish and spread evenly. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
While the cake is baking, make the frosting: Beat together the butter and peanut butter until smooth and creamy. Gradually add the powdered sugar, 1/2 cup at a time, beating well after each addition. Add the milk and vanilla extract, then beat until smooth and fluffy.
When the cake is done, remove it from the oven and let it cool completely in the baking dish.
Once cooled, spread the peanut butter frosting evenly over the top. Slice and enjoy!

For a chocolate twist, add 1/2 cup cocoa powder to the dry ingredients.

Use crunchy peanut butter instead of creamy for extra texture.

Substitute all-purpose flour with a gluten-free blend to make it gluten-free.

Add chopped peanuts on top of the frosting for added crunch.

For lighter frosting, use cream cheese mixed with peanut butter instead of all butter.

Store covered at room temperature for up to 2 days or refrigerated up to 5 days.

Reheat slices gently in the microwave for about 15 seconds to soften frosting.

Use almond or oat milk as a non-dairy alternative to whole milk.

If frosting is too thick, add milk a teaspoon at a time; if too thin, add more powdered sugar.