Peanut Butter Sheet Cake with Peanut Butter Frosting

Introduction

Peanut Butter Sheet Cake with Peanut Butter Frosting is a rich, soft, and ultra-moist dessert that peanut butter lovers can’t resist. Made with a simple yellow cake mix and topped with a creamy homemade peanut butter frosting, this easy sheet cake recipe is perfect for parties, potlucks, family gatherings, or anytime you’re craving a classic peanut butter dessert.

This peanut butter cake is incredibly easy to prepare, requires minimal ingredients, and bakes in a single pan, making it ideal for beginner bakers and busy schedules.

Ingredients

For the Peanut Butter Sheet Cake

1 box yellow cake mix
4 large eggs
½ cup unsalted butter, softened
¾ cup creamy peanut butter
½ cup milk
¼ cup vegetable oil
1 teaspoon vanilla extract

For the Peanut Butter Frosting

½ cup unsalted butter, softened
1 cup creamy peanut butter
2–3 cups powdered sugar (adjust for sweetness)
2–4 tablespoons milk or heavy cream
1 teaspoon vanilla extract
Pinch of salt (optional)

Instructions

Step 1: Preheat the Oven

Preheat your oven to 180°C (350°F).
Grease a 9×13-inch sheet cake pan with butter or nonstick spray and set aside.

Step 2: Prepare the Cake Batter

In a large mixing bowl, add:

Yellow cake mix
Eggs
Softened butter
Peanut butter
Milk
Vegetable oil
Vanilla extract

Using a hand mixer or stand mixer, beat on medium speed for 2–3 minutes until the batter is smooth, creamy, and well combined.

Step 3: Bake the Cake

Pour the batter evenly into the prepared pan.
Smooth the top with a spatula.

Bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean.

Remove the cake from the oven and let it cool completely in the pan before frosting.

How to Make Peanut Butter Frosting

Step 4: Prepare the Frosting

In a medium bowl, beat the softened butter and peanut butter together until smooth and fluffy.

Gradually add powdered sugar, one cup at a time, mixing well after each addition.

Add vanilla extract and 2 tablespoons of milk.
Beat until creamy. Add more milk if needed to reach a smooth, spreadable consistency.

Step 5: Frost the Cake

Once the cake is completely cool, spread the peanut butter frosting evenly over the top using a spatula or knife.

For a decorative finish, swirl the frosting or sprinkle crushed peanuts on top.

Tips for the Best Peanut Butter Sheet Cake

Use creamy peanut butter for the smoothest texture
Make sure the cake is fully cooled before frosting
Don’t overbake — this keeps the cake moist
Adjust powdered sugar to control sweetness

Variations

Chocolate Peanut Butter Cake: Add chocolate chips to the batter
Peanut Butter & Jelly Cake: Spread a thin layer of strawberry or grape jam under the frosting
Crunchy Topping: Add chopped peanuts or Reese’s pieces on top
Extra Rich: Drizzle with melted chocolate

Storage Instructions

Store the peanut butter sheet cake in an airtight container at room temperature for 2 days, or in the refrigerator for up to 5 days.

Freezing Instructions

Wrap individual slices tightly in plastic wrap and freeze for up to 2 months.
Thaw at room temperature before serving.

Final Thoughts

This Peanut Butter Sheet Cake with Peanut Butter Frosting is an easy, crowd-pleasing dessert that delivers big flavor with minimal effort. Soft, moist cake paired with creamy peanut butter frosting makes this recipe a guaranteed hit every time.