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Peanut Butter Sheet Cake

  • Total Time: 55 mins
  • Yield: 18 1x




  • ¼ cup creamy peanut butter (I used homemade)
  • 1 cup water
  • 1 stick unsalted butter, cut into pieces
  • 1 cup granulated sugar
  • 1 cup packed light brown sugar
  • 2 cups all-purpose flour
  • ½ teaspoon kosher salt
  • 1 teaspoon baking soda
  • 2 large eggs
  • ½ cup milk (I used almond milk)
  • 1 teaspoon pure vanilla extract


  • 1 ½ sticks unsalted butter, cut into pieces
  • 6 tablespoons milk (I used almond milk)
  • ½ cup creamy peanut butter – not natural or homemade
  • 3 ½ cups confectioners’ sugar
  • 1 tablespoon pure vanilla extract


  1. Preheat oven to 375 degrees F. Butter a 9 by 13 inch pan.
  2. Make the cake. In a medium saucepan, combine peanut butter, water, and butter over medium heat and bring to a boil. Remove from the heat.
  3. In a medium bowl, stir together sugars, flour, salt, and baking soda until combined. Add this mixture to the peanut butter mixture and mix together in the pot. Add the eggs, milk, and vanilla to the pot and mix until combined. Pour into the prepared pan. Bake for 20-25 minutes, rotating halfway through if necessary, until a toothpick inserted in the center of the cake comes out with only a few moist crumbs.
  4. Make the frosting. In a small saucepan, combine butter, milk, and peanut butter over medium heat. Bring to a boil and then remove from the heat. Add vanilla. Stir in confectioners’ sugar a little at a time until the frosting has thickened considerably but is still quite runny. Pour over the warm cake. Best served warm, but may be stored in an airtight container overnight. May also be frozen, wrapped in parchment and foil and placed in a zipper bag for up to 3 months. Thaw at room temperature for several hours, or in a 350 degree F oven, wrapped in parchment, placed on top of foil for about 15 minutes.


Recipe adapted from The Girl Who Ate Everything

  • Prep Time: 30 mins
  • Cook Time: 25 mins