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- 1
Prep the pan and oven
Preheat your oven to 350 degrees F and grease a 15x10x1-inch baking pan. This shallow pan is what gives you that quick-baking, tender sheet cake. If a 15x10 is all you have in a 13x9, you can use the smaller pan, but it'll be very full and need a few extra minutes in the oven.
- 2
Whisk the dry ingredients
In a large bowl, whisk together the flour, 2 cups of the sugar, the baking soda, and the salt. Whisking now evenly distributes the leavening so your cake rises consistently across the whole pan.
- 3
Make the peanut butter mixture
In a saucepan, combine the water and 3/4 cup (1-1/2 sticks) of the butter, cubed, and bring just to a boil. Stir in 1/2 cup of the chunky peanut butter and the canola oil until smooth, then remove from the heat. The oil is your secret to a soft, moist crumb, and warming the peanut butter helps it blend in seamlessly.
- 4
Combine wet and dry
Pour the warm peanut butter mixture into the flour mixture and stir to combine. In a small bowl, whisk the eggs (room temperature so they blend evenly), buttermilk, and 1 teaspoon of the vanilla until smooth, then add to the batter, whisking constantly. Stop as soon as it comes together. Overmixing builds gluten, and too much gluten turns a light cake dense and gummy.
- 5
Bake
Pour the batter into the prepared pan and bake on the middle rack until a toothpick inserted in the center comes out clean, 20 to 25 minutes. Start checking at 20; a shallow cake goes from perfect to dry quickly.
- 6
Make the glaze
While the cake bakes, combine the remaining 2/3 cup sugar, the evaporated milk, and 1 tablespoon butter in a saucepan over medium heat. Bring to a boil, stirring constantly, then cook and stir for 2 minutes. Remove from the heat and stir in the remaining 1/3 cup chunky peanut butter, the marshmallows, and remaining 1/2 teaspoon vanilla until smooth. The marshmallows melt right in and help the glaze set into a soft, fudgy layer.
- 7
Glaze and cool
Spoon the warm glaze over the warm cake and spread evenly. Glazing while both are warm lets it sink in slightly and set into that signature glossy top. Cool on a wire rack and let the glaze firm up before slicing.
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Peanut Butter Sheet Cake
Created by: SugarAndButter
Ingredients
- 2 cup all-purpose flour
- 2 2/3 cup sugar
- 1 tsp baking soda
- 1/2 tsp salt
- 1 cup water
- 0.81 cup butter
- 5/6 cup chunky peanut butter
- 1/4 cup canola oil
- 2 eggs
- 1/2 cup buttermilk
- 1 1/2 tsp vanilla extract
- 1/3 cup evaporated milk
- 1/3 cup miniature marshmallows
Instructions
- Prep the pan and ovenPreheat your oven to 350 degrees F and grease a 15x10x1-inch baking pan. This shallow pan is what gives you that quick-baking, tender sheet cake. If a 15x10 is all you have in a 13x9, you can use the smaller pan, but it'll be very full and need a few extra minutes in the oven.
- Whisk the dry ingredientsIn a large bowl, whisk together the flour, 2 cups of the sugar, the baking soda, and the salt. Whisking now evenly distributes the leavening so your cake rises consistently across the whole pan.
- Make the peanut butter mixtureIn a saucepan, combine the water and 3/4 cup (1-1/2 sticks) of the butter, cubed, and bring just to a boil. Stir in 1/2 cup of the chunky peanut butter and the canola oil until smooth, then remove from the heat. The oil is your secret to a soft, moist crumb, and warming the peanut butter helps it blend in seamlessly.
- Combine wet and dryPour the warm peanut butter mixture into the flour mixture and stir to combine. In a small bowl, whisk the eggs (room temperature so they blend evenly), buttermilk, and 1 teaspoon of the vanilla until smooth, then add to the batter, whisking constantly. Stop as soon as it comes together. Overmixing builds gluten, and too much gluten turns a light cake dense and gummy.
- BakePour the batter into the prepared pan and bake on the middle rack until a toothpick inserted in the center comes out clean, 20 to 25 minutes. Start checking at 20; a shallow cake goes from perfect to dry quickly.
- Make the glazeWhile the cake bakes, combine the remaining 2/3 cup sugar, the evaporated milk, and 1 tablespoon butter in a saucepan over medium heat. Bring to a boil, stirring constantly, then cook and stir for 2 minutes. Remove from the heat and stir in the remaining 1/3 cup chunky peanut butter, the marshmallows, and remaining 1/2 teaspoon vanilla until smooth. The marshmallows melt right in and help the glaze set into a soft, fudgy layer.
- Glaze and coolSpoon the warm glaze over the warm cake and spread evenly. Glazing while both are warm lets it sink in slightly and set into that signature glossy top. Cool on a wire rack and let the glaze firm up before slicing.