This Peanut Butter Sheet Cake is an easy dessert made in a 9×13-inch pan that is perfect for sharing. It is soft, tender, and packed with rich peanut butter flavor, with a sweet peanut butter swirl baked right into the cake.
You can enjoy this cake as-is for a simple peanut butter treat, or add a creamy peanut butter frosting on top for an extra special dessert. And if you love classic peanut butter desserts, my Chewy Peanut Butter Cookies are another favorite you will want to try!
Ingredients & Substitutions
- Peanut butter: Creamy peanut butter gives this cake its rich peanut butter flavor. Most is mixed into the batter, and the remaining peanut butter is warmed and swirled into the top of the cake for an extra pop of peanut butter flavor. Use a regular creamy peanut butter for the best texture. Avoid natural peanut butter, as the oil separation can affect the cake.
- Butter, brown sugar, and granulated sugar: This combination adds richness and sweetness, and helps create a soft, tender cake. Use unsalted butter so you can control the salt in the recipe.
- Eggs: Use room temperature eggs for a smoother batter and better texture.
- Buttermilk and sour cream: These keep the cake soft and moist. You can substitute full-fat Greek yogurt for the sour cream.
- All-purpose flour, baking soda, and kosher salt: These dry ingredients create the structure for the cake while keeping it light and tender.
- Peanut butter frosting (optional): The creamy peanut butter frosting adds an extra layer of peanut butter flavor. You can also enjoy the cake without frosting for a simpler dessert.
- Heavy cream: Heavy cream creates a rich, smooth frosting that spreads easily. You can substitute whole milk if that is what you have, but you may need slightly less since it is thinner than heavy cream.
Tips for the Best Peanut Butter Sheet Cake
- Use regular creamy peanut butter. Avoid natural peanut butter, which can separate and affect the texture of both the cake and the frosting.
- Bring refrigerated ingredients to room temperature. Room temperature eggs, buttermilk, and sour cream mix more easily for a smooth, even batter.
- Warm the peanut butter before swirling. A few seconds in the microwave makes it easier to drizzle and swirl into the batter without tearing the cake.
- Do not overmix the batter. Mix just until the flour is incorporated to keep the cake soft and tender.
- Do not overbake. Check the cake near the end of the baking time. A toothpick should come out with a few moist crumbs for the best texture.
- Cool completely before frosting. If you choose to add the optional peanut butter frosting, make sure the cake is completely cool so the frosting stays smooth and spreadable.
FAQs
Do I have to add the peanut butter frosting?
No! This Peanut Butter Sheet Cake is soft, moist, and full of peanut butter flavor all on its own. (I love the peanut butter swirl in there!) The optional peanut butter frosting makes it even richer, but the cake is delicious with or without it.
Can I use natural peanut butter?
I do not recommend it. Regular creamy peanut butter gives this cake the best texture and consistency. Natural peanut butter tends to separate, which can affect both the cake and the frosting.
Can I add mix-ins to Peanut Butter Sheet Cake?
Yes! This cake is easy to customize. Try folding in peanut butter chips, chocolate chips, chopped peanut butter cups, or chopped roasted peanuts before spreading the batter into the pan. Keep the total amount of mix-ins to about 1 cup so the cake bakes evenly.
Can I use a different pan size?
This recipe is designed for a 9×13-inch baking pan. If you use a different size pan, the baking time and thickness of the cake will change, so be sure to watch it closely for doneness.
Can I freeze Peanut Butter Sheet Cake?
Yes! You can freeze the unfrosted or frosted cake. Wrap individual slices or the whole cake tightly in plastic wrap and aluminum foil, then freeze for up to 3 months. Thaw at room temperature before serving.
How to Store Peanut Butter Sheet Cake
If the cake is unfrosted, cover it tightly or store it in an airtight container at room temperature for up to 3 days.
If the cake is frosted, store it in an airtight container at room temperature for up to 2 days or in the refrigerator for up to 5 days. Let the refrigerated cake come to room temperature before serving for the best texture and flavor.
To freeze, wrap the whole cake or individual slices tightly in plastic wrap, followed by aluminum foil, and freeze for up to 3 months. Thaw overnight in the refrigerator or at room temperature before serving.
Peanut Butter Sheet Cake
Ingredients
Peanut Butter Cake
- 1 â…“ cups (344 g) creamy peanut butter, divided
- ½ cup (1 stick / 113 g) unsalted butter, softened
- 1 cup (200 g) light brown sugar, packed
- ½ cup (100 g) granulated sugar
- 2 large eggs, room temperature
- 2 teaspoons vanilla extract
- 1 cup (240 g) buttermilk, room temperature
- ½ cup (120 g) sour cream, room temperature
- 2 ¼ cups (281 g) all-purpose flour
- 1 teaspoon baking soda
- ½ teaspoon kosher salt
Peanut Butter Frosting (Optional)
- ½ cup (129 g) creamy peanut butter
- ½ cup (1 stick / 113 g) unsalted butter, softened
- 3 cups (375 g) confectioners' sugar
- â…“ cup (80 g) heavy whipping cream, plus more as needed
- 1 teaspoon vanilla extract
- Pinch of kosher salt
Instructions
Peanut Butter Cake
- Preheat oven to 350°F (177°C). Spray a 9×13-inch baking pan with nonstick cooking spray and line with parchment paper, leaving an overhang for easy removal.
- In a large bowl or the bowl of a stand mixer, beat 1 cup of the peanut butter and the butter together until smooth and creamy, about 1 to 2 minutes.
- Add the brown sugar and granulated sugar. Beat until light and fluffy, about 2 to 3 minutes.
- Add the eggs one at a time, mixing well after each addition. Add the vanilla extract and mix until combined.
- In a separate bowl, whisk together the flour, baking soda, and salt.
- Gradually add the dry ingredients and the buttermilk and sour cream to the peanut butter mixture, alternating between each addition. Begin and end with the dry ingredients. Mix just until combined. Do not overmix.
- Spread the batter evenly into the prepared pan.
- Warm the remaining â…“ cup peanut butter until smooth and easy to drizzle. Drop spoonfuls over the cake batter, then use a knife to gently swirl the peanut butter into the batter.
- Bake for 28 to 33 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Do not overbake.
- Let the cake cool completely in the pan before adding frosting.
Peanut Butter Frosting (Optional)
- In a large bowl, beat the peanut butter and butter together until smooth and creamy.
- Add the confectioners’ sugar, vanilla, salt, and heavy cream. Mix on low speed until combined, then increase the speed and beat until light and fluffy. Add more cream, 1 tablespoon at a time, until the frosting reaches a smooth, spreadable consistency.
- Spread the frosting over the cooled cake.
Did you make this recipe?
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