Peanut Butter Sheet Cake with Chocolate Frosting

Blogger Bree Hester of Baked Bree makes a simple chocolate-frosted peanut butter cake that your family will love!

  • Prep Time 15 min
  • Total Time 1 hr 40 min
  • Servings 12


box Betty Crocker™ SuperMoist™ yellow cake mix
1 1/3
cups water
cup peanut butter
cup vegetable oil
teaspoon vanilla


cup butter
cup unsweetened baking cocoa
cup milk
teaspoon vanilla
3 3/4
cups powdered sugar

  • 1 Heat oven to 350°F (325°F for dark or nonstick pan). Spray bottom and sides of 13x9-inch pan with baking spray with flour.
  • 2 In large bowl, beat all cake ingredients with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. Pour into pan.
  • 3 Bake 20 to 25 minutes or until toothpick inserted in center comes out clean.
  • 4 In 2-quart saucepan, heat butter, cocoa and milk to boiling over medium heat. Remove from heat; stir in 1 teaspoon vanilla. Gradually add powered sugar, beating until mixture is blended and smooth. Pour frosting over warm cake.
  • 5 Cool completely in pan on cooling rack, about 1 hour. Cut into 4 rows by 3 rows.

Expert Tips

To make a thinner cake, use a 15x10x1-inch pan and reduce the baking time by 5 minutes.

To add even more peanut butter and chocolate flavor, top the cake with chopped chocolate-covered peanut butter cup candies.