Peanut Butter Sheet Cake
This peanut butter sheet cake is a moist, from-scratch American classic topped with a rich cooked peanut butter frosting. It's designed to feed a crowd and comes together with pantry staples.
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This peanut butter sheet cake is a moist, from-scratch American classic topped with a rich cooked peanut butter frosting. It's designed to feed a crowd and comes together with pantry staples.
Delivery in as fast as one hour.*
Prices vary by store
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Preheat your oven to 350°F (175°C).
In a medium saucepan, combine 1/2 cup peanut butter, water, and vegetable oil. Heat over medium heat, stirring occasionally, until the peanut butter is melted and the mixture is smooth.
In a large mixing bowl, whisk together the self-rising flour and granulated sugar.
Pour the hot peanut butter mixture into the dry ingredients and stir until just combined.
In a separate small bowl or measuring cup, whisk together the buttermilk, eggs, and 1 tsp of vanilla extract.
Pour the buttermilk mixture into the cake batter and mix until everything is well incorporated.
Grease a standard sheet pan (approximately 18x13 inches) with butter or non-stick cooking spray.
Pour the batter into the prepared pan and use a spatula to spread it evenly.
Bake for 15-20 minutes, or until a toothpick inserted into the center comes out clean.
While the cake is baking, prepare the frosting. In a saucepan, combine 1/2 cup peanut butter and milk. Heat over medium heat until melted and smooth.
Remove the saucepan from the heat, stir in 1 tsp of vanilla extract, then add the powdered sugar. Mix until the frosting is smooth and combined.
Once the cake is out of the oven, immediately pour the warm frosting over the warm cake.
Use a spoon or spatula to spread the frosting evenly over the entire surface of the cake.
Let the cake cool slightly before slicing and serving.
Cover cooled cake with plastic wrap or store in an airtight container at room temperature for up to 2 days, or refrigerate for up to 4 days. Frosted cake can be reheated gently in a 300°F oven for 10 minutes.
Yes. The baked cake keeps covered at room temperature for 2 days, or refrigerated for up to 4 days. Apply frosting no more than 24 hours before serving to maintain texture.
Self-rising flour already contains baking powder and salt, which gives this cake its rise and structure. All-purpose flour would require added baking powder and salt separately.
The cooked frosting method creates a thicker, fudgier texture that sets up firmer on the cake. It's a traditional technique for sheet cakes that prevents a greasy mouthfeel.
Creamy peanut butter is recommended for a smooth batter and frosting. Natural peanut butter with separated oils may result in a grainier texture.
Insert a toothpick in the center—it should come out with just a few moist crumbs, not wet batter. The cake should also spring back when lightly touched.
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