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Peanut butter marshmallow brownies on a white table with a blue napkin.
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4.70 from 10 votes

Peanut Butter and Marshmallow Brownies

If you love the yummy taste of a classic peanut butter and fluff sandwich, you will love these Peanut Butter & Marshmallow Brownies. My classic brownie recipe is made even tastier with swirls of Marshmallow Fluff. These are so good that you will not be able to eat just one!
Prep Time5 minutes
Cook Time25 minutes
Total Time30 minutes
Course: Dinner
Cuisine: American
Keyword: Chewy Peanut Butter Chocolate Chip Cookies, peanut butter brownies
Servings: 12 brownies
Calories: 254cal
Author: Amy Desrosiers
Cost: $3


  • 11" x 9" brownies


  • 1 cup all-purpose flour
  • 1 tsp. baking powder
  • 2/3 cup granulated sugar
  • 1/2 cup brown sugar
  • 1/8 tsp. kosher salt
  • 1 tsp vanilla extract
  • 1/2 cup creamy or chunky peanut butter
  • 1/3 cup butter melted
  • 2 large eggs
  • 1/2 cup marshmallow fluff warmed for 15 seconds.


  • Preheat oven to 350 degrees Fahrenheit. Line an 11″x 9″ brownie pan with parchment paper so you can easily lift your brownies right out once they are cooled. (This is optional, but makes removing the brownies and cleaning way easier!)
  • In a large bowl, whisk the dry ingredients together.
  • Add the wet ingredients directly to the dry ingredients, and mix thoroughly with a wooden spoon.
  • Spread the batter onto a parchment-lined brownie pan. Spread evenly in the pan with a rubber spatula.
  • Add 5-6 small plops of warmed marshmallow to the top of your batter. Use a wooden skewer to swirl the marshmallow on top of their brownies.
  • Bake on center rack of your oven for 25 minutes. Brownies will have a golden brown edge and moist (but not raw) inner.
  • Allow brownies to cool for at least one hour before cutting. Cooling will also let the brownies naturally harden a bit.
  • Remove brownies from pan and use a wet knife to cut them into 12 pieces.


Nutritional values may vary and are meant to be a guide.  


Serving: 1g | Calories: 254cal | Carbohydrates: 35g | Protein: 5g | Fat: 11g | Saturated Fat: 5g | Cholesterol: 45mg | Sodium: 129mg | Potassium: 146mg | Fiber: 1g | Sugar: 24g | Vitamin A: 203IU | Calcium: 38mg | Iron: 1mg