Name: Peanut Butter Sheet Cake with Peanut Butter Frosting
Prep time: 15 min
Cook time: 25 min
Total time: 50 min
Cuisine: American
Ingredients: 2 cups all-purpose flour; 2 cups granulated sugar; 1 tsp baking soda; 1/2 tsp salt; 2 large eggs; 1/2 cup sour cream or Greek yogurt; 1/2 cup milk; 1 cup creamy peanut butter; 1/2 cup unsalted butter; 1 cup water; 1 tsp vanilla extract; For the frosting:; 1/2 cup unsalted butter; 1/2 cup creamy peanut butter; 1/3 cup milk; 3 cups powdered sugar; 1 tsp vanilla extract; Pinch of salt (optional)

This peanut butter sheet cake with peanut butter frosting is pure comfort in every bite. It’s soft, moist, and packed with rich peanut butter flavor, then topped with a creamy, slightly salty-sweet frosting that melts in the mouth. Whether I’m baking for a gathering or just craving a nostalgic dessert, this cake always delivers.

Why You’ll Love This Recipe

I love this cake because it’s simple to make but tastes like something special. The sheet cake format makes it perfect for feeding a crowd, and the peanut butter flavor is bold without being overwhelming. The frosting is what ties it all together—warm, smooth, and poured right over the cake so it seeps into every corner. It’s a must-bake for peanut butter lovers like me.

ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

For the cake:

All-purpose flour
Granulated sugar
Baking soda
Salt
Eggs
Sour cream or Greek yogurt
Milk
Creamy peanut butter
Unsalted butter
Water
Vanilla extract

For the frosting:

Unsalted butter
Creamy peanut butter
Milk
Powdered sugar
Vanilla extract
Pinch of salt (optional, for balance)

directions

I start by preheating the oven to 350°F (175°C) and greasing a 9×13-inch baking pan.
In a large bowl, I whisk together the flour, sugar, baking soda, and salt.
In a saucepan, I combine the peanut butter, butter, and water. I bring it to a light boil, then remove it from heat and stir it into the dry ingredients.
In a separate bowl, I whisk the eggs, sour cream, milk, and vanilla, then mix that into the batter until smooth.
I pour the batter into the prepared pan and bake for 22–25 minutes, or until a toothpick inserted in the center comes out clean.
While the cake bakes, I make the frosting. In a saucepan, I melt the butter and peanut butter together, then stir in milk and vanilla. Off the heat, I whisk in powdered sugar until smooth.
I pour the warm frosting over the warm cake and gently spread it to the edges. It sets into a luscious, slightly crackly finish as it cools.

Servings and timing

This recipe serves about 15 to 20 people. It takes 15 minutes to prep, 25 minutes to bake, and 10 more to frost and set. So I can have it ready in under an hour.

Variations

I sometimes add chopped peanuts on top for a bit of crunch or swirl in a bit of melted chocolate before baking for a peanut butter cup twist. For a slightly lighter version, I use plain Greek yogurt instead of sour cream. And when I’m feeling indulgent, I top the frosting with mini chocolate chips or a drizzle of caramel.

storage/reheating

I store the cake tightly covered at room temperature for up to 3 days or in the fridge for up to a week. To reheat, I warm slices in the microwave for 10–15 seconds—it brings back that fresh-from-the-oven softness. The cake also freezes well, either whole or in slices, wrapped tightly.

FAQs

Can I make this cake ahead of time?

Yes, I often bake it a day ahead. I let it cool completely, cover it, and keep it at room temperature. The flavor deepens overnight.

What kind of peanut butter works best?

I use creamy, shelf-stable peanut butter for the smoothest results. Natural peanut butter can separate and affect texture.

Can I use a different pan size?

Yes, I’ve used a jelly roll pan for a thinner cake or doubled the recipe for a half-sheet pan. I just adjust the baking time accordingly.

Is the frosting too sweet?

It’s rich but balanced. If I want it less sweet, I reduce the powdered sugar slightly and add a pinch of salt for contrast.

Can I turn this into cupcakes?

Absolutely. I scoop the batter into lined muffin tins and bake for 15–18 minutes. Then I frost each one individually.

Conclusion

This peanut butter sheet cake with peanut butter frosting is my go-to when I want a rich, nostalgic dessert that’s easy to make and share. It’s soft, sweet, and filled with classic peanut butter flavor. Whether for birthdays, potlucks, or simple weeknight cravings, it never fails to impress—and I always find myself going back for seconds.