Peanut Butter Sheet Cake
This Peanut Butter Sheet Cake is soft, fluffy, and packed with rich peanut butter flavor in every bite. The tender cake is topped with a warm, creamy peanut butter frosting that melts right into the surface. It’s an easy crowd-pleasing dessert that’s perfect for potlucks, parties, or anytime you’re craving a homemade peanut butter treat.
Servings: 20
Calories: 323kcal
Equipment
- 10x15-inch jelly roll pan
- Parchment Paper optional, for easy removal and to prevent sticking
- Large bowl
- Medium saucepan
- Wooden spoon or spatula
- Toothpick
Ingredients
For the Cake
- 2 cups all-purpose flour
- 2 cups granulated sugar
- 1/2 tsp baking soda
- 1/4 tsp salt
- 1 cup water
- 3/4 cup butter
- 1/2 cup peanut butter
- 1/4 cup vegetable oil
- 2 eggs large
- 1/2 cup buttermilk
- 1 tsp vanilla extract
For the Frosting
- 2/3 cup granulated sugar
- 1/3 cup evaporated milk
- 1 tbsp butter
- 1/3 cup chunky peanut butter
- 1/3 cup marshmallows miniature
- 1/2 tsp vanilla extract
Instructions
- Preheat the oven to 350°F. Grease a 10x15-inch jelly roll pan, or line it with parchment paper for easier removal. In a large bowl, mix together the flour, sugar, baking soda, and salt.
- In a saucepan, bring the water and butter to a boil. Remove from heat and stir in the peanut butter and vegetable oil until smooth. Pour this mixture into the dry ingredients and stir to combine.
- In a separate bowl, whisk together the eggs, buttermilk, and vanilla extract. Add to the batter and mix until smooth and fully combined.
- Spread the batter evenly into the prepared pan.
- Bake for 18 to 26 minutes, or until a toothpick inserted in the center comes out clean.
- While the cake is baking, combine the sugar, evaporated milk, and butter in a saucepan. Bring to a boil, stirring constantly, and boil for 2 minutes.
- Remove the frosting mixture from heat and stir in the peanut butter, marshmallows, and vanilla until smooth and the marshmallows are fully melted.
- Spoon the warm frosting over the hot cake and spread evenly. Let cool completely before slicing and serving.
Notes
- Frost the cake while it is still warm so the frosting slightly melts into the top for the best texture.
- Lining the pan with parchment paper makes cleanup easier and helps ensure the cake doesn’t stick.
Nutrition
Calories: 323kcal | Carbohydrates: 40g | Protein: 5g | Fat: 17g | Saturated Fat: 7g | Polyunsaturated Fat: 3g | Monounsaturated Fat: 6g | Trans Fat: 0.3g | Cholesterol: 38mg | Sodium: 181mg | Potassium: 104mg | Fiber: 1g | Sugar: 29g | Vitamin A: 274IU | Vitamin C: 0.1mg | Calcium: 30mg | Iron: 1mg