Peanut Butter Sheet Cake with Fluffy Peanut Butter Frosting: A Nutty Indulgence

Peanut butter lovers, rejoice! This Peanut Butter Sheet Cake with Fluffy Peanut Butter Frosting is moist, tender, and loaded with rich peanut butter flavor. Unlike traditional layered cakes, this sheet cake is simple to make, easy to serve, and perfect for birthdays, potlucks, or cozy weekend treats. The highlight is the airy, creamy peanut butter frosting, which takes the cake from delicious to absolutely irresistible.

This recipe avoids chocolate entirely, letting the peanut flavor shine. The cake is soft, slightly dense, and melts in your mouth, while the frosting is light, fluffy, and sweetened just right. With a sprinkle of crushed peanuts on top, each bite has added crunch, making it a crowd favorite.

Ingredients

For the Cake:

• 2 cups all-purpose flour
• 2 tsp baking powder
• 1/2 tsp baking soda
• 1/2 tsp salt
• 1/2 cup unsalted butter, softened
• 1 cup creamy peanut butter
• 1 1/2 cups brown sugar, packed
• 2 large eggs
• 1 tsp vanilla extract
• 1 cup milk

For the Fluffy Peanut Butter Frosting:

• 1 cup unsalted butter, softened
• 1 cup creamy peanut butter
• 3 cups powdered sugar, sifted
• 1/4 cup milk (add more if needed for consistency)
• 1 tsp vanilla extract
• Optional: crushed peanuts for garnish

Instructions

1. Preheat the oven: to 350°F (175°C). Grease a 9×13-inch baking pan or line with parchment paper.
2. Mix dry ingredients: In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
3. Cream butter and peanut butter: In a large bowl, beat butter, peanut butter, and brown sugar until smooth and creamy. Add eggs one at a time, beating well after each addition. Stir in vanilla extract.
4. Combine wet and dry ingredients: Alternately add dry ingredients and milk to the peanut butter mixture, beginning and ending with dry ingredients. Mix until smooth and fully combined.
5. Bake: Pour batter into prepared pan and smooth the top. Bake 30–35 minutes, or until a toothpick inserted in the center comes out clean. Cool completely in the pan on a wire rack before frosting.
6. Prepare frosting: In a large bowl, beat butter and peanut butter until fluffy. Gradually add powdered sugar, then vanilla. Slowly add milk until desired creamy consistency is achieved.
7. Frost the cake: Spread frosting evenly over cooled cake. Sprinkle crushed peanuts on top for texture and visual appeal.
8. Serve and enjoy: Slice into squares and serve. Store leftovers in an airtight container at room temperature for up to 3 days or refrigerate for up to a week.

Tips for the Perfect Peanut Butter Sheet Cake

• Room temperature ingredients: Make sure butter, eggs, and milk are at room temperature to ensure a smooth batter.
• Peanut butter choice: Use creamy peanut butter for a silky texture. Natural peanut butter can work but may alter consistency.
• Frosting consistency: If frosting is too thick, add a little extra milk, one teaspoon at a time. Too thin? Add more powdered sugar.
• Nut garnish: Toasting crushed peanuts lightly enhances flavor and adds crunch.

Peanut Butter Sheet Cake with Fluffy Peanut Butter Frosting

A moist, nutty peanut butter sheet cake topped with fluffy peanut butter frosting and crushed peanuts.

Print Recipe Pin Recipe

Prep Time 20 minutes mins

Cook Time 35 minutes mins

Total Time 55 minutes mins

Servings: 12 servings

Course: Dessert

Cuisine: American

Calories: 360

Ingredients Equipment Method Notes

Ingredients

  

Cake

• 2 cups all-purpose flour
• 2 tsp baking powder
• 0.5 tsp baking soda
• 0.5 tsp salt
• 0.5 cup unsalted butter softened
• 1 cup creamy peanut butter
• 1.5 cups brown sugar packed
• 2 eggs large
• 1 tsp vanilla extract
• 1 cup milk

Frosting

• 1 cup unsalted butter softened
• 1 cup creamy peanut butter
• 3 cups powdered sugar sifted
• 0.25 cup milk add more if needed for consistency
• 1 tsp vanilla extract
• crushed peanuts optional garnish

Equipment

• Mixing bowls
• 9×13-inch baking pan
• Wire rack
• Hand mixer or stand mixer

Method

 

1. Preheat oven to 350°F (175°C). Grease a 9×13-inch pan or line with parchment paper.
2. Whisk flour, baking powder, baking soda, and salt in a medium bowl.
3. Beat butter, peanut butter, and brown sugar until creamy. Add eggs one at a time, then vanilla.
4. Alternately add dry ingredients and milk to the peanut butter mixture until smooth.
5. Pour batter into pan and smooth top. Bake 30–35 minutes until a toothpick comes out clean. Cool completely.
6. Beat butter and peanut butter until fluffy. Gradually add powdered sugar, vanilla, and milk to reach desired consistency.
7. Spread frosting evenly over cooled cake and sprinkle crushed peanuts on top.
8. Slice and serve. Store leftovers in an airtight container.

Notes

You can make this cake a day ahead. Optional: drizzle with melted chocolate for variation.

Fun Variations

1. Chocolate Peanut Butter Combo: Drizzle melted chocolate over the frosting or swirl it into the cake batter for a chocolate-peanut twist.
2. Peanut Butter Banana Cake: Fold in mashed bananas into the batter for a naturally sweet, moist variation.
3. Mini Sheet Cakes: Make in 8×8 pans for individual servings or gift-sized treats.
4. Vegan Version: Substitute butter with vegan margarine, eggs with flax eggs, and milk with almond or oat milk.

Serving Suggestions

• Pair with a glass of cold milk or a warm cup of coffee.
• Serve with whipped cream for extra indulgence.
• Top slices with chocolate chips or caramel drizzle for a decadent touch.

Fun Fact / Cultural Context

Peanut butter cake is a classic American dessert that gained popularity in the mid-20th century, coinciding with the rise of creamy, mass-produced peanut butter. While chocolate often dominates dessert tables, peanut butter sheet cakes show off the nutty, savory-sweet flavor profile that has captivated generations. Fluffy peanut butter frosting elevates this simple cake to a celebratory treat without needing elaborate layers.