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4.56 from 9 votes

White Chocolate Peanut Butter Bars

White Chocolate Peanut Butter Bars - Deliciously peanut butter cake bars topped with a dreamy white chocolate buttercream and Reese's mini white chocolate peanut butter cups. PB lover inspired! 
Author: Kim Lange


Peanut Butter Sheet Cake:

  • 1 cup all-purpose flour
  • 1 cup sugar
  • 1/3 teaspoon salt
  • 1/2 teaspoon baking powder
  • 1/2 cup butter
  • 1/2 cup water
  • 3 tablespoons creamy peanut butter
  • 1 egg beaten
  • 1 teaspoon vanilla extract
  • 1/4 cup buttermilk, or any milk will work

White Chocolate Buttercream Frosting:

  • 1 cup unsalted butter softened softened
  • 12 ounces white chocolate melted and cooled slightly
  • 1 cup confectioners' sugar
  • 1 teaspoon pure vanilla extract
  • 1/4 teaspoon salt
  • 1 package of Reese's Mini White Chocolate Peanut Butter Cups roughly chopped


White Chocolate Peanut Butter Bars:

  • Preheat oven to 350 degrees.
  • Sift together flour, sugar, salt and baking powder in a large bowl, then set aside.
  • Combine butter, water and peanut butter in a saucepan over medium heat and bring to a boil.  Add in the flour mixture and whisk together, then set aside.
  • Combine egg, vanilla and buttermilk and whisk together, then transfer to peanut butter mixture and mix well until everything is just incorporated.
  • Spread into a greased 9x13 pan. This cake will rise so when you put in it pan, it will appear as a thin layer.
  • Bake for 12-17 minutes, until it springs back when gently touched.

White Chocolate Buttercream:

  • Using a mixer, beat the butter at medium speed until creamy. Beat in the melted white chocolate. Add in the confectioners' sugar, salt and vanilla and beat at low speed until light and fluffy.
  • Add more confectioners sugar for a more stiff frosting, but add it 1/4 cup at a time.
  • Sprinkle the chopped peanut butter cups on top. 
    Cut and serve!


Double the recipe for a 11X17 inch sheet/jellyroll pan for a crowd!  Cut the recipe in half for 8x8 pan.