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+ servings

Peanut Butter Cookie Bars with Butterfinger Frosting

Peanut Butter Cookie Bars are our favorite soft, chewy peanut butter cookies in bar form then slathered in a layer of creamy peanut butter and topped with decadent Butterfinger chocolate frosting! This Peanut Butter Cookie Bars recipe is what dreams are made of. 
Prep Time 15 minutes
Cook Time 15 minutes
Total Time 30 minutes
Servings 60


Wet Ingredients

  • 1 cup brown sugar
  • 1 cup granulated sugar
  • 1 cup (2 sticks) butter, softened
  • 1/2 cup crunchy peanut butter *
  • 2 eggs
  • 2 teaspoons vanilla extract

Dry Ingredients

  • 2 cups all-purpose flour
  • 2 cups quick oats
  • 1 teaspoon baking soda
  • 1/2 teaspoon baking powder
  • 1/2 teaspoon salt
  • 1 teaspoon ground cinnamon

Peanut Butter Layer

  • 1 cup smooth peanut butter

Butterfinger Chocolate Frosting

  • 1/2 cup butter
  • 1/2 cup unsweetened cocoa powder
  • 2 3.7 oz. King Size Butterfinger Bars finely crushed (I use my food processor),
  • 2 cups sifted powdered sugar
  • 1/2 teaspoon vanilla extract
  • 1/3 cup evaporated milk plus more as needed

Topping (optional)

  • 1/2 3.7 oz. King Size Butterfinger Bars finely crushed (I use my food processor)


  • In a stand or electric mixer, cream butter and sugars until light and fluffy. Beat in 1/2 cup crunchy peanut butter. Add eggs and vanilla and mix until just combined.
  • In a separate bowl, mix together the Dry Ingredients until well combined. Add Dry Ingredients to Wet Ingredients and mix a few times then proceed to mix by hand (the dough will be thick) until evenly combined.
  • Lightly grease a large 12" x 17" jelly roll pan and add cookie dough. Spread dough out into an even layer.** Bake at 350F degrees for 12-15 or until edges are barely golden.
  • While the cookie is still hot, top with spoonfuls of 1 cup smooth peanut butter. Let sit 30 seconds or so for the peanut butter to melt a little to become more spreadable. Once spreadable, smooth peanut butter evenly over cookie with a spatula. Let cool.
  • Meanwhile (you can do the first part while your cookie is baking), prepare Butterfinger Chocolate Frosting by melting butter in a medium saucepan. Stir in cocoa powder and bring to a boil for 1 minute. Let cool (I put mine in the refrigerator). Once cool, transfer to a mixing bowl and beat in Butterfingers, powdered sugar and vanilla until combined (it will be thick). Slowly beat in evaporated milk to reach desired consistency.
  • Spread frosting over cooled peanut butter layer. Sprinkle with crushed Butterfinger crumbs (optional).


*May substitute smooth peanut butter but I love the extra crunch. **I have found the easiest way to evenly spread cookie dough is to top the dough in the pan with a large sheet of parchment paper (larger than the size of the pan) then roll it out using a rolling pin over the parchment paper until even.