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Marshmallow Peanut Butter Chocolate Chip Cookie Bars
Prep Time
30 mins
Cook Time
25 mins
Total Time
55 mins
These Marshmallow Peanut Butter Chocolate Chip Cookie Bars are rich, gooey, and completely over-the-top. These peanut butter chocolate chip cookie bars are filled with Reeses peanut butter cups, chocolate chips, and marshmallow fluff. These cookie bars are ridiculously rich and entirely worth it.
Course: Dessert
Cuisine: American
Keyword: Marshmallow Peanut Butter Chocolate Chip Cookie Bars
Servings: 9 or 12 Cookie Bars
Author: Michelle
  • 1/2 cup peanut butter, room temperature (I used all-natural)
  • 1/2 cup butter, softened to room temperature
  • 1 cup brown sugar
  • 3/4 cup granulated sugar
  • 2 eggs
  • 2 1/2 tsp vanilla extract
  • 1 tsp baking soda
  • 1 tsp salt
  • 2 1/2 cups all purpose flour
  • 1 cup Reeses peanut butter cups, chopped into small pieces
  • 1 cup semi-sweet chocolate chips
  • 1 7 oz jar marshmallow fluff
  1. Preheat oven to 350 degrees and line a 9x9 or 11x7 baking dish with non-stick foil or grease with baking spray (9x9 will yield thicker bars while 11x7 will be slightly thinner). Set aside.
  2. In a bowl, mix butter and peanut butter together until combined.
  3. Add in brown sugar and granulated sugar, and mix until combined.
  4. Add in eggs, one at a time, stirring well after each addition.
  5. Mix in vanilla extract.
  6. Add in baking soda, salt, and all-purpose flour, and mix until combined.
  7. Lastly, add in Reeses peanut butter cups (chopped into small pieces) and chocolate chips, mixing until combined (dough will be thick).
  8. Spread half of the dough evenly over the bottom of the pan. Set aside the rest of the dough.
  9. Spread the marshmallow fluff on top of the dough (the marshmallow fluff is sticky, but spread it out as best you can).
  10. Press/spread the remaining dough on top of the marshmallow fluff in an even layer(it’s okay if some of the marshmallow fluff is showing).
  11. Bake for about 25 minutes, or until the top is lightly golden brown.
  12. Allow the bars to cool for at least 30 minutes (I prefer to cool for at least an hour) before cutting into them.
  13. Enjoy!
  14. Store remaining bars in an airtight container (they’re fine at room temperature, if it’s not too hot, for up to 4-5 days).