Peanut Butter Bars are loaded with peanut butter and topped with peanut butter butterscotch frosting and chopped Reese’s peanut butter cups. Try my Peanut Butter and Jelly Bars for another favorite treat or snack bar!

Stack of Peanut Butter Reese's Bars on a White Plate

Peanut Butter Bars

These peanut butter bars are soft, chewy, and full of peanut butter flavor in every bite! Plus, more peanut butter with butterscotch chips is added to the topping. And, I had to add a hint of chocolate (and more peanut butter) when I added the chopped Reese’s peanut butter cups. So, I can assure you that if you love peanut butter, you will definitely be a fan of this dessert. And then you will want to make my Reese’s Ooey Gooey Bars!


Peanut Butter Reese's Bars Process of melting ingredients and adding ingredients into a saucepan

Bar Ingredients

There are two main parts to this recipe–the bars and the peanut butter topping. The bars are delicious on their own but don’t skimp on the topping if you want even more peanut butter flavor. (Plus, the topping is also delicious on ice cream!)

Room Temperature Ingredients: Using room temperature ingredients (specifically eggs in this case) will help you get the best results when baking these bars. 

Peanut Butter: I used creamy peanut butter for the bars and chunky peanut butter for the topping. You could use all creamy or even all chunky if that is what you have on hand.

Eggs: You will need two whole eggs and one additional egg yolk. Be sure to add each egg one at a time before adding another one; this ensures the egg will emulsify with the butter.

Reese’s Peanut Butter Cups: Chop up about a cup of mini Reese’s peanut butter cups to add to the top of the bars for the final touch and a little chocolate.

Pouring Sauce over Peanut Butter Bars

Can I Make These Bars in a Different Size Pan?

Yes! If you don’t have an 11×15-inch sheet pan (or jelly roll pan), you can make these in a 9×13-inch baking dish or even a 9x9x2-inch dish. However, just be aware that the baking times will be different since the bars will be thicker. As for the sauce, you shouldn’t have too much leftover, if any, depending on how thick you pour it on.

Peanut Butter Reese's Bar on a White Plate with Fork

More Delicious Bars

Peanut Butter Bars

Prep Time 15 minutes
Cook Time 20 minutes
Total Time 35 minutes
Peanut Butter Bars are loaded with peanut butter and topped with peanut butter butterscotch frosting and chopped Reese's peanut butter cups.



  • 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 11×15-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.

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Meet Amanda Rettke

Amanda Rettke is the creator of I Am Baker, and the bestselling author of Surprise Inside Cakes: Amazing Cakes for Every Occasion – With a Little Something Extra Inside.Over the course of her 15+ year blogging adventure, she has been featured in and collaborated with the Food Network, New York Times, LA Times, Country Living Magazine, People Magazine, Epicurious, Brides, Romantic Homes, life:beautiful, Publishers Weekly, The Daily Mail, Star Tribune, The Globe and Mail, DailyCandy, YumSugar, The Knot, The Kitchn, and Parade, to name a few.

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