Go Back
+ servings

Peanut Butter Bars

Peanut Butter Bars are loaded with peanut butter and topped with peanut butter butterscotch frosting and chopped Reese's peanut butter cups.
Prep Time15 mins
Cook Time20 mins
Total Time35 mins
Course: Dessert, Snack
Keyword: Peanut Butter Bars
Servings: 15 bars
Calories: 464kcal
Author: Amanda Rettke--iambaker.net



  • ¾ cup (1½ sticks / 170 g) unsalted butter, melted
  • cups (350 g) light brown sugar, packed
  • ¾ cup (193.5 g) creamy peanut butter
  • 2 large eggs + 1 egg yolk, room temperature
  • teaspoons vanilla extract
  • cups (285 g) all-purpose flour
  • 2 teaspoons cornstarch
  • 1 teaspoon baking powder
  • 1 teaspoon kosher salt

Peanut Butter Topping

  • ½ cup (1 stick / 113 g) unsalted butter
  • ½ cup (129 g) chunky peanut butter
  • ½ cup (85 g) butterscotch chips
  • 1 cup miniature Reese's peanut butter cups, roughly chopped



  • Preheat the oven to 350°F and line an 11x15-inch sheet pan with parchment paper (or lightly grease and flour).
  • In a large bowl, combine the melted butter and brown sugar. Stir well.
  • Add peanut butter and mix until creamy.
  • Add the eggs and the egg yolk, one at a time, stirring well after each addition.
  • Stir in the vanilla extract.
  • In a separate, medium-sized bowl, whisk together the flour, cornstarch, baking powder, and salt.
  • Gradually stir the flour mixture into the butter and egg mixture until completely combined.
  • Spread the batter evenly into the prepared pan. Firmly press the batter into the pan into a flat, even layer. (We used another piece of parchment to press down on the batter.)
  • Bake for 15-20 minutes, or until the edges just begin to turn golden brown.
  • Allow the bars to cool completely before adding the peanut butter sauce.

Peanut Butter Topping

  • In a medium saucepan, melt butter and peanut butter over medium-low heat. Once they are fully melted and combined, add in butterscotch chips. Remove from heat and stir continually until mostly melted. (There will be chunks in the bottom of the pan, but this is okay.) Set aside to cool slightly.
  • Pour the sauce over the cooled bars, spreading it with a spatula if needed.
  • Top with chopped Reese's peanut butter cups.
  • Set the pan of bars in the refrigerator to allow the peanut butter topping to set (3-5 minutes) before cutting and enjoying.


Calories: 464kcal