Yield: 20 servings

Peanut Butter Sheet Cake

Prep Time 15 minutes
Cook Time 15 minutes
Additional Time 15 minutes
Total Time 45 minutes

This Peanut Butter Sheet Cake is an unbelievably moist, rich, peanut butter cake with creamy peanut butter frosting poured on top. Similar to Texas Sheet Cake, but for the peanut butter lover instead!


For the cake

  • ¼ cup peanut butter
  • 1 cup water
  • ½ cup unsalted butter
  • 1 cup granulated sugar
  • 1 cup light brown sugar, packed
  • 2 cups all-purpose flour
  • 1 teaspoon kosher salt
  • 1 teaspoon baking soda
  • 2 large eggs
  • ½ cup buttermilk
  • 1 teaspoon vanilla extract

For the frosting

  • ¾ cup unsalted butter
  • 6 Tablespoons buttermilk
  • ½ cup peanut butter
  • 3 ½ cups powdered sugar
  • 1 Tablespoon vanilla extract


  1. Preheat oven to 375 degrees F. Line a cookie sheet 12x18-inch (sheet pan size) with parchment paper. Set aside.
  2. In a LARGE saucepan, combine peanut butter, water, and butter for the cake. Bring to a boil, while stirring constantly. Once boiling, remove from heat. Add in sugars, flour, salt and baking soda. Mix until well combined. Add in eggs, buttermilk, and vanilla until blended. Pour into prepared baking sheet and bake for 15 minutes.
  3. While the cake is baking, prepare the frosting. In a saucepan, combine butter, buttermilk, and peanut butter. Bring to a boil, while stirring.
  4. Remove from heat and add in powdered sugar and vanilla extract. Whisk until smooth. Pour over warm cake.


  • Don't have buttermilk handy? You can make a buttermilk substitute to use in this recipe.
  • Unsalted butter is my preference here (and for most cakes and frostings). If you only have salted butter that will work, too, just reduce the amount of salt called for in the recipe.
  • Too much peanut butter? Use my favorite chocolate buttercream instead!
  • Love sheet cakes? Try our delicious Watergate Sheet Cake next!
  • Storage: Store at room temperature in airtight container or covered with plastic wrap for up to four days. Freeze for up to 3 months.

Nutrition Information:



Serving Size:

1 slice

Amount Per Serving: Calories: 366Total Fat: 17gSaturated Fat: 8gTrans Fat: 0gUnsaturated Fat: 7gCholesterol: 50mgSodium: 258mgCarbohydrates: 51gFiber: 1gSugar: 39gProtein: 5g

*Nutrition facts are an estimate and not guaranteed to be accurate. Please see a registered dietitian for special diet advice.

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