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Peanut Butter Sheet Cake
5 from 82 votes

Peanut Butter Sheet Cake

Peanut Butter Sheet Cake is a moist cake baked in a large pan, combining peanut butter, butter, sugars, and buttermilk. The batter is combined with heated peanut butter and butter mixture, then mixed with eggs and vanilla. It is topped with a fudgy peanut butter frosting that balances sweetness and saltiness.

Prep Time
25 mins
Cook Time
32 mins
Total Time
57 mins
Servings: 24 servings
Calories: 354 kcal
Course: Dessert, Cake
Cuisine: American

Ingredients

Sheet Cake
  • 2 cups all-purpose flour
  • 1 cup granulated sugar
  • ¾ cups light brown sugar firmly packed
  • ¾ teaspoon baking soda
  • ¾ teaspoon salt
  • 1 cup water
  • ¾ cup butter cut into pieces, unsalted
  • ¼ cup avocado oil or canola oil or vegetable oil
  • ½ cup peanut butter creamy
  • ½ cup buttermilk
  • 2 egg room temperature preferred, large
  • 1 ½ teaspoons vanilla extract
Fudgy Peanut Butter Frosting
  • 4 cups powdered sugar
  • ½ cup buttermilk
  • 10 Tablespoons butter cut into pieces, unsalted
  • ⅔ cup peanut butter creamy
  • ¼ salt heaping teaspoon
  • 1 teaspoon vanilla extract

Instructions

    Cup of Yum
  1. Preheat oven to 350F (175C) and lightly grease a 13x9 baking pan. Set aside.
  2. In a large bowl, whisk together flour, sugars, baking soda, and salt.
  3. In a medium-sized saucepan, combine water, butter, and oil. Heat over medium heat, stirring occasionally until butter is melted and bring to a boil.
  4. Once boiling, remove from heat and add peanut butter. Stir until peanut butter is dissolved and mixture is smooth. Add to bowl with dry ingredients and stir until combined. Set aside to cool for 5-10 minutes.
  5. Meanwhile, in a separate bowl, whisk together buttermilk, eggs, and vanilla extract.
  6. Gradually stir buttermilk mixture into batter, stirring until just combined.
  7. Pour batter evenly into prepared pan and transfer to center rack of 350F (175C) preheated oven and bake for 30-32 minutes or until a toothpick inserted in the center comes out clean or with moist crumbs. Prepare frosting.
Fudgy Peanut Butter Frosting
  1. Measure out sugar and set aside (if you’re worried about lumps in your icing, sift the sugar after measuring).
  2. Combine buttermilk, butter, peanut butter, and salt in a medium-sized saucepan. Cook over medium-low heat until butter is melted. Increase heat to medium and bring to a boil while stirring constantly. Once boiling, remove from heat.
  3. Immediately add powdered sugar and vanilla extract.
  4. Whisk until smooth and immediately pour evenly over cake (in the pan, I do not remove my cake from the pan).

Notes

  • Creamy peanut butter is best for smooth texture, but crunchy can be used for added bits.
  • Baking in a 15x10-inch jelly roll pan takes about 18-22 minutes at 350°F.
  • Avoid natural peanut butter with separated oil to maintain cake texture.
  • Cover and store cake at room temperature up to three days.

Nutrition Information

Serving 1serving Calories 354kcal (18%) Carbohydrates 46g (15%) Protein 5g (10%) Fat 18g (28%) Saturated Fat 8g (40%) Polyunsaturated Fat 2g (12%) Monounsaturated Fat 6g (30%) Trans Fat 0.4g (20%) Cholesterol 43mg (14%) Sodium 181mg (8%) Potassium 114mg (2%) Fiber 1g (4%) Sugar 36g (72%) Vitamin A 359IU (7%) Calcium 31mg (3%) Iron 1mg (6%)

Nutrition Facts

Serving: 24 servings

Amount Per Serving

Calories 354

% Daily Value*

Serving 1serving
Calories 354kcal 18%
Carbohydrates 46g 15%
Protein 5g 10%
Fat 18g 28%
Saturated Fat 8g 40%
Polyunsaturated Fat 2g 12%
Monounsaturated Fat 6g 30%
Trans Fat 0.4g 20%
Cholesterol 43mg 14%
Sodium 181mg 8%
Potassium 114mg 2%
Fiber 1g 4%
Sugar 36g 72%
Vitamin A 359IU 7%
Calcium 31mg 3%
Iron 1mg 6%

* Percent Daily Values are based on a 2,000 calorie diet.