These super fudgy Marshmallow Brownies are topped with a layer of marshmallows as well as a chocolate, peanut butter, and Rice Krispies mixture. They’re ultra-rich, chocolatey, and decadent — the perfect way to satisfy your sweet tooth whenever it strikes!

a stack of these fudgey marshmallow crunch brownie bars

You’ve Never Had Brownies Like This!

If you love fudgy brownies and can’t resist crazy brownie concoctions, you are absolutely, positively going to love these brownie bars. They’re part brownie, part s’more, and part Rice Krispy treat. It’s everything you know and love, baked up into one amazing dessert!

These were my go-to party dessert for ages, until I eventually made a peanut butter cup version).

I’m fairly certain that I don’t need to convince anyone here that these brownies are the ultimate in fabulous ideas. A couple of notes for you since I first made these brownie beauts …

  • I am keeping the brownie recipe the same below in case anyone wants to keep using the original recipe. However, I totally recommend using my better-than-box-mix brownies as the base recipe. It has become my go-to brownie recipe, and I think it’s the best first layer when making delicious brownie concoctions.
  • I have successfully made the top layer using both Sunbutter (Natural Sunbutter with the yellow lid) and almond butter (Barney Butter smooth). I do not recommend using any peanut butter or other nut butter with a lot of oil separation or the top layer will not set properly. Both of the previously mentioned products mimic the same consistency of regular peanut butter.
a baking sheet of these fudgey marshmallow crunch brownie bars

Key Ingredients

These Marshmallow Brownie Bars are threefold — the brownie base, the layer of marshmallow cream, and the crispy chocolate peanut butter layer on top. 

For the brownies, you’ll need: unsweetened chocolate (I recommend a high-quality chocolate bar like Guittard), unsalted butter, semisweet chocolate chips. all-purpose flour, baking powder, salt, eggs (at room temperature), granulated sugar, and pure vanilla extract.

For the marshmallow layer, all you need is a bag of mini marshmallows. 

And for the crispy chocolate peanut butter layer, you’ll need: milk chocolate chips, creamy peanut butter, unsalted butter, and Rice Krispies cereal. That’s it!

How To Make These Brownies

  • First, do the prep work. Preheat your oven to 350 degrees F, and grease a 9×13-inch pan.
  • Next, make the brownies. Make the batter as directed, then bake for 25 to 30 minutes, or until a toothpick inserted into the corner of of the pan comes out with moist crumbs.
a baking tray of of these uncooked fudgey marshmallow crunch brownie bars
  • Make the marshmallow layer. Remove the brownies from the oven and immediately sprinkle the marshmallows over them. Return the pan to the oven for 3 more minutes.
Making the marshmallow cream layer for these marshmallow crunch brownie bars
  • Then, make the crispy chocolate peanut butter layer. Place the milk chocolate chips, peanut butter, and tablespoon of butter in a medium saucepan. Melt over low heat, stirring constantly, until completely melted. Remove from heat, add the Rice Krispies and mix well. Allow to cool for 3 minutes. Spread the mixture evenly over the marshmallow layer. Allow the assembled brownies to cool to room temperature, and then refrigerate for 30 minutes to make it easier to slice. Serve with a glass of cold milk, and enjoy!
the chocolate peanut butter rice krispies layer of these marshmallow crunch brownie barsa

Storage and Freezing Instructions

  • Storage: The brownies can be stored at room temperature or in the refrigerator for up to 1 week in an airtight container.
  • Freezing: Wrap individual brownies in plastic wrap and place in an airtight container or freezer bag for up to 3 months. Thaw at room temperature.

Tips and Variations

  • Drizzle these prepared Marshmallow Crunch Brownie Bars with some salted caramel, melted chocolate, or melted peanut butter!
  • If you like nuts in your brownies, feel free to add some chopped pecans or walnuts to the brownie batter!
a stack of these fudgey marshmallow crunch brownie bars

More Recipes To Try

a stack of these fudgey marshmallow crunch brownie bars

Marshmallow Brownies

Super fudgy brownies topped with a layer of marshmallows and a chocolate, peanut butter and Rice Krispies mixture.
3.91 (42 ratings)

Ingredients

For the Brownie Base

  • 4 ounces (113.4 g) unsweetened chocolate
  • cup (151.33 g) unsalted butter
  • cups (225 g) semisweet chocolate chips, divided
  • 1⅓ cups (166.67 g) all-purpose flour
  • 1 teaspoon baking powder
  • ½ teaspoon (0.5 teaspoon) salt
  • 4 eggs, at room temperature
  • 2 cups (400 g) granulated sugar
  • 2 teaspoons vanilla extract

For the Marshmallow Layer

  • 10.5 ounce (297.67 g) bag miniature marshmallows

For the Crispy Chocolate Peanut Butter Layer

  • cups (366 ml) milk chocolate chips
  • 1 cup (258 g) smooth peanut butter
  • 1 tablespoon unsalted butter
  • cups (42 g) Rice Krispies cereal

Instructions 

  • Make the Brownies: Preheat the oven to 350 degrees F. Grease a 9×13-inch pan.
  • In a medium saucepan, melt the unsweetened chocolate, butter and ¾ cup of the semisweet chocolate chips over medium heat. Stir occasionally while melting. Set aside and cool for 5 minutes.
  • In a large bowl, whisk the eggs thoroughly. Add the sugar and vanilla, and whisk until well blended. Stir the melted ingredients into the egg mixture, mixing well. Sift the flour, baking powder and salt into the mixture and stir well. Fold in the remaining ½ cup semisweet chocolate chips.
  • Pour the batter into the prepared pan, smoothing it into an even layer. Bake for 25 to 30 minutes, or until a toothpick inserted into the corner of of the pan comes out with moist crumbs.
  • Remove the brownies from the oven and immediately sprinkle the marshmallows over them. Return the pan to the oven for 3 more minutes.
  • Make the Crispy Chocolate Peanut Butter Layer: Meanwhile, place the milk chocolate chips, peanut butter, and tablespoon of butter in a medium saucepan. Melt over low heat, stirring constantly, until completely melted. Remove from heat, add the Rice Krispies and mix well. Allow to cool for 3 minutes.
  • Spread the mixture evenly over the marshmallow layer. Allow to cool to room temperature, then refrigerate for 30 minutes to make it easier to slice. The brownies can be stored at room temperature or in the refrigerator for up to 1 week.

Notes

  • Equipment: 9×13-inch baking pan
  • Brownies: Use your favorite brownie recipe (or a box mix!) that will yield a 9×13-inch pan of brownies. I’m partial to my better-than-box-mix brownies recipe.
  • Peanut Butter Note: Do not use natural peanut butter, as it is too oily.
  • Peanut Butter Substitutes: I have successfully made the top layer using both Sunbutter (Natural Sunbutter with the yellow lid) and almond butter (Barney Butter smooth).
  • Storage: The brownies can be stored at room temperature or in the refrigerator for up to 1 week in an airtight container.
  • Freezing: Wrap individual brownies in plastic wrap and place in an airtight container or freezer bag for up to 3 months. Thaw at room temperature.
  • Recipe adapted from How Sweet Eats.
Nutritional values are based on one serving
Calories: 340kcal, Carbohydrates: 44g, Protein: 6g, Fat: 16g, Saturated Fat: 8g, Cholesterol: 44mg, Sodium: 145mg, Potassium: 222mg, Fiber: 2g, Sugar: 29g, Vitamin A: 360IU, Vitamin C: 1.1mg, Calcium: 45mg, Iron: 2.6mg

Did you make this recipe?

Leave a review below, then snap a picture and tag @thebrowneyedbaker on Instagram so I can see it!

Photography by Dee Frances.