Peanut Butter Sheet Cake with Fluffy Peanut Butter Frosting – The Ultimate Dessert for Peanut Butter Lovers

If you’ve been searching for the perfect peanut butter dessert — soft, rich, deeply peanut-buttery, and topped with a cloud-like fluffy frosting — this Peanut Butter Sheet Cake with Fluffy Peanut Butter Frosting is about to become your new favorite bake. This cake is everything a peanut butter lover dreams of: moist, tender, comforting, and topped with a whipped, silky frosting that melts on your tongue.

Unlike many peanut butter cakes that turn out dense or dry, this sheet cake stays incredibly soft thanks to a warm peanut butter batter, a splash of milk, and the perfect balance of fats. The frosting is light but still full of flavor, whipping together peanut butter, butter, powdered sugar, and cream to create an irresistible topping that spreads like a dream.

Whether you’re baking for a potluck, birthday, holiday party, picnic, or just because you want a decadent treat at home, this sheet cake delivers every time. It’s easy, beautiful, and guaranteed to disappear fast.

Let’s dive into the ingredients, steps, and all the tips you need to create the perfect peanut butter sheet cake.

Why You’ll Love This Peanut Butter Sheet Cake

✔ Soft, moist, melt-in-your-mouth texture

Warm peanut butter melts seamlessly into the batter.

✔ Fluffy, creamy peanut butter frosting

Whipped to perfection for a silky, cloud-like finish.

✔ Easy, no-fuss sheet cake

Feeds a crowd and requires no special decorating skills.

✔ Perfect for any occasion

Birthdays, bake sales, potlucks, picnics — it travels perfectly.

✔ Peanut butter in every bite

Both the cake and frosting are loaded with peanut butter flavor.

✔ Customizable

Add peanuts, chocolate chips, drizzle, or even a swirl of jam.

Ingredients

Cake

• 2 cups all-purpose flour
• 1 ½ cups sugar
• 1 tsp baking soda
• ½ tsp salt
• 1 cup water
• ½ cup milk
• ½ cup unsalted butter
• ½ cup creamy peanut butter
• 2 eggs
• 1 tsp vanilla extract

Fluffy Peanut Butter Frosting

• ½ cup unsalted butter, softened
• ¾ cup creamy peanut butter
• 3 cups powdered sugar
• ¼ cup heavy cream or milk
• 1 tsp vanilla extract
• Pinch of salt

Optional Toppings

• Chopped peanuts
• Mini chocolate chips
• Peanut butter drizzle
• Crushed pretzels

Instructions

1. Make the Cake Batter

Preheat oven to 350°F (175°C). Grease a 10×15 inch jelly roll pan.

In a large bowl, whisk together flour, sugar, salt, and baking soda.

2. Heat the Wet Mixture

In a saucepan, combine water, butter, and peanut butter.
Heat over medium until melted and smooth.
Pour the warm mixture over the dry ingredients and stir gently.

3. Add Eggs & Milk

Mix in milk, eggs, and vanilla until smooth.

4. Bake

Pour batter into prepared sheet pan and bake 18–22 minutes, or until a toothpick comes out clean.

5. Make the Fluffy Peanut Butter Frosting

Beat softened butter and peanut butter until creamy.
Add powdered sugar gradually.
Beat in heavy cream and vanilla until light and fluffy (about 2–3 minutes).

6. Frost the Cake

Let cake cool completely.
Spread frosting generously over the top.
Add toppings if desired.

Peanut Butter Sheet Cake with Fluffy Peanut Butter Frosting

A soft, moist peanut butter sheet cake topped with ultra-fluffy peanut butter frosting. Easy to make, perfect for crowds, and packed with peanut butter flavor.

Print Recipe Pin Recipe

Prep Time 15 minutes mins

Cook Time 22 minutes mins

Total Time 37 minutes mins

Servings: 20 squares

Course: Cake, Dessert

Cuisine: American

Calories: 285

Ingredients

  

Cake

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

Fluffy Peanut Butter Frosting

• 0.5 cup butter softened
• 0.75 cup creamy peanut butter
• 3 cups powdered sugar
• 0.25 cup heavy cream
• 1 tsp vanilla extract
• 1 pinch salt

Equipment

• Jelly roll pan
• Saucepan
• Mixing bowls
• Electric mixer

Method

 

1. Preheat oven to 350°F and grease a 10×15 jelly roll pan.
2. Whisk together flour, sugar, baking soda, and salt.
3. Heat butter, peanut butter, and water until melted; pour into dry ingredients.
4. Mix in eggs, milk, and vanilla until smooth.
5. Bake 18–22 minutes until a toothpick comes out clean.
6. Beat butter and peanut butter; add powdered sugar, cream, and vanilla to make frosting.
7. Spread frosting over cooled cake and garnish as desired.

Notes

Do not use natural peanut butter for best texture. Add peanuts or chocolate chips for extra crunch.

Tips for the Best Peanut Butter Sheet Cake

✔ Use creamy peanut butter

Avoid natural peanut butter, which separates and affects texture.

✔ Spread the frosting while it’s fluffy

Freshly whipped frosting spreads effortlessly.

✔ Warm up peanut butter mixture fully

Warm batter results in a tender, moist cake.

✔ Don’t overbake

Pull from oven as soon as the center is set.

✔ Customize with toppings

Peanuts add crunch; chocolate adds richness; jam adds nostalgia.

Variations

Chocolate Peanut Butter Sheet Cake

Add ¼ cup cocoa powder to the batter and chocolate chips on top.

Peanut Butter & Jelly Sheet Cake

Drizzle jam into the frosting and swirl with a knife.

Reese’s Cake

Add chopped Reese’s cups to the batter and sprinkle more on top.

Salted Pretzel Peanut Butter Cake

Add crushed pretzels for salty-sweet perfection.

Peanut Butter Banana Cake

Add 1 mashed banana to the wet ingredients.

Serving Suggestions

Serve with:

• A glass of cold milk
• Vanilla ice cream
• Whipped cream
• Hot coffee or espresso

You can also cut it into:

• Large bakery-style squares
• Bite-size mini bars
• Layered dessert parfaits

Storage & Freezing

Room Temperature

Up to 3 days in an airtight container.

Refrigerator

Up to 5–6 days; bring to room temp before serving.

Freezer

Freeze unfrosted cake for up to 2 months.
Freeze frosting separately or make fresh.

Fun Food Facts

• Peanut butter was introduced at the 1904 World’s Fair and has been an American classic ever since.
• Sheet cakes rose to popularity in the 1960s for potlucks and church dinners.
• Peanut butter pairs exceptionally well with flaky sea salt, chocolate, caramel, and bananas.