I LOVE brownies and this chocolatey marshmallow brownie is my new favorite. Brownies with marshmallows? Great. Brownies with marshmallow cream? Great. Marshmallows AND marshmallow fluff in brownies? THE BEST. These fudgy brownies aren’t too sweet, even with the addition of marshmallows and marshmallow fluff. The top of the brownies gets slightly crisp and paired with the gooey marshmallows, every bite is a textured dream. I think I hear the leftovers calling my name…

If you, like me, can’t get enough of brownies, make sure to check out some of my other favorite brownie recipes. My Ferrero Rocher Brownies, Black Cocoa Brownies, and Homemade Cosmic Brownies are all made from scratch. If you’re looking for something a little simpler, I’ve got you covered – I have several recipes that take a boxed brownie mix and make it spectacular, like my Oreo Truffle Brownies or Peppermint Bark Brownies. Yum!

A hand holding a square of Marshmallow Brownies, with marshmallow creme swirled into the top.

Why This Recipe Works

  • Double dosage of marshmallow goodness. There are recipes for brownies with marshmallows and brownies with marshmallow fluff, but this recipe has both, because we deserve it.
  • Butter AND oil work together. The butter in these brownies helps to add flavor, while vegetable oil makes a chewy brownie instead of a cakey brownie.
  • Deep chocolate flavor. There are many elements to this recipe that create chocolate decadence. First, using Dutch process cocoa. Second, blooming the cocoa in boiling water, and third, using a dark chocolate bar in addition to cocoa powder.

Ingredient Notes

  • Dutch process cocoa: This type of cocoa has a more intense chocolatey flavor than regular unsweetened cocoa. For more information about Dutch process cocoa, check out my Best Cocoa Powder for Baking guide.
  • Boiling water: Adding a hot liquid like water or coffee to cocoa powder helps extract more chocolate flavor. This process is called “blooming.”
  • Butter: Butter adds a caramelized, rich flavor to brownies.
  • Oil: Oil helps create dense, moist, and fudgy marshmallow brownies.
  • Eggs: This recipe uses one whole egg plus an additional egg yolk. 
  • Dark chocolate: Dark chocolate adds a little bit of sweetness to these brownies as well as additional chocolate flavor. I used 72%, but you can use 50-60%.
  • Granulated sugar: Because I used dark chocolate instead of unsweetened chocolate, I lowered the amount of sugar used so these brownies wouldn’t be too sweet. 
  • Semi-sweet chocolate chips: I like brownies that have a lot of stuff in them, so when you take a bite, it’s a symphony of texture and flavor. Semi-sweet chocolate chips are a delicious addition here and a good contrast to the sweetness of the marshmallows. 
  • Mini marshmallows and marshmallow cream: Some marshmallow brownie recipes use only marshmallows, and others use only marshmallow cream or fluff. Here, I’ve combined the best of both worlds for the ultimate marshmallow brownies.
Marshmallow Brownies ingredients on a baking sheet, each portioned into glass bowls.

Step-by-Step Instructions

  1. Preheat the oven and prepare your pan. Adjust an oven rack to the middle of your oven and preheat to 350℉. Line an 8×8-inch pan with parchment paper and leave some paper over the sides so you can easily remove your brownies. Use cooking spray to grease the parchment paper.
  2. Whisk together boiling water and cocoa. Mix 5 tablespoons boiling water and 2½ tablespoons cocoa powder in a large bowl until smooth, then add 1 oz dark chocolate and whisk until it’s melted.
  3. Whisk in melted butter and oil. Add 2 tablespoons of melted unsalted butter and 5 tablespoons of vegetable oil. Mix thoroughly. Your mixture may look clumpy and curdled at this point but don’t worry, that’s normal. 
  4. Add egg, extra egg yolk, vanilla, and sugar. Mix your eggs and 1 teaspoon of vanilla extract with your chocolate mixture until you have a smooth batter, then add ¾ cup of granulated sugar and mix thoroughly.
  5. Add in dry ingredients. Fold in flour, chocolate chips, salt, and mini marshmallows. Using a spatula, gently mix in ¾ cup of all-purpose flour, ½ teaspoon salt, ¼ cup semi-sweet chocolate chips, and 1 cup mini marshmallows into your wet ingredients. Feel free to make the chocolate chips and marshmallows “heaping” cups. Be careful not to overmix.
Four images showing how to make marshmallow brownie batter with mini marshmallow brownies in the batter.
  1. Pour batter into prepared pan. Using a rubber spatula, scrape every last bit of batter into your prepared baking pan and spread it into an even layer.
  2. Swirl in marshmallow fluff. Microwave ⅓ cup marshmallow fluff in a microwave-safe bowl for 10-15 seconds to make it soft and easy to work with. Dollop the fluff on top of the brownie batter and then carefully swirl it into the batter with a knife. Admire your beautiful marshmallow swirl brownies.
  3. Bake and enjoy! Bake your brownies for 28-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs, but not liquid batter attached. Careful not to overbake, as this will dry out your brownies. Remove your pan from the oven and place on a wire rack to cool completely. Once the brownies are cool, you can lift the parchment out of the baking dish and onto a cutting board to cut the brownies and serve. Don’t worry – they will still be gooey chocolate brownies even after they’ve cooled.
Brownies with marshmallows and marshmallow creme (fluff) that is swirled into the top of the brownies.

Recipe Tips

You can use unsweetened cocoa powder or “natural” cocoa powder in this recipe. The brownies won’t be as chocolatey but they will still be scrumptious. 

If your parchment paper is giving you trouble, crumple it up into a ball before spreading it out in your pan. Crumpling the parchment paper makes it easier to lay it flat and shape it the way you want. 

Make these marshmallow peppermint brownies by adding a ½ teaspoon of peppermint extract to the batter.

Make these rocky road brownies by adding a quarter cup of toasted, chopped almonds.

Turn this marshmallow brownie recipe into s’mores brownies by breaking graham crackers and laying them in your pan before pouring brownie batter on top, or adding a graham cracker crust.

Make Ahead, Storing, and Freezing

Make Ahead: Brownies are best when they’re fresh, although these will be delicious for several days. Since the brownies need to cool before they are cut, you can make them 2-3 hours before serving, or in the morning to serve in the evening. 

Storing: Store leftover brownies in an airtight container at room temperature for 3-4 days. The airtight container will keep the brownies from drying out. Do not place them in the fridge, as the marshmallows and marshmallow creme will harden, and the brownies will dry out.

Freezing: Good news – these brownies can be frozen so you can keep them for emergency snack breaks. Let brownies cool completely, wrap them in plastic wrap and place in an airtight container. They can stay in the freezer for up to two months. Remove and let thaw in the fridge, then come to room temperature on the counter.

A made from scratch brownie recipe with marshmallows in the batter and marshmallow cream swirled into the top and baked.

Recipe FAQs

What does the extra egg yolk do?

Using an additional egg yolk enhances the rich flavor of baked goods. Using an additional egg yolk instead of a whole egg also helps these brownies to stay dense and moist. A whole egg would make these brownies more cakey.

What can I do with the leftover egg white?

You can store leftover egg whites in the fridge for up to four days. Mix them into oatmeal for a protein boost. You can also freeze egg whites for up to a year, although they’re best if used within two months. Use egg whites to make meringue, mousse, or even your own marshmallows!

Can I use brown sugar instead of granulated sugar?

You can substitute brown sugar for granulated sugar in a 1-1 ratio. However, this will affect the texture of your brownie, making it heavier.

What happens if I overmix my brownie batter?

Overmixing brownie batter incorporates more air into it, creating a more cakey brownie. Avoid overmixing for a more dense, fudgy brownie.

Why are my brownies dry?

Dry brownies are typically overbaked. When you insert a toothpick or knife into the center of your brownies, it should come away with a few moist crumbs clinging to it – if it comes out clean, the brownies are overbaked.

Overhead photo of Marshmallow Brownies cut into squares on a white parchment paper with mini marshmallows scattered around.

More Brownie Recipes

More Marshmallow Recipes

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A hand holding a Marshmallow Brownie that has marshmallow cream/fluff that was swirled into the top of the brownie before baking.
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Marshmallow Brownies

These fudgy marshmallow brownies are loaded with mini marshmallows and swirled with marshmallow fluff prior to baking.
Prep Time: 15 minutes
Cook Time: 30 minutes
Total Time: 45 minutes
Servings: 16 brownies

Ingredients
 

  • 2 1/2 tablespoons Dutch processs cocoa
  • 5 tablespoons boiling water
  • 1 oz dark chocolate - finely chopped (I used 72% cocoa)
  • 2 tablespoons unsalted butter - melted
  • 5 tablespoons vegetable oil
  • 1 large egg
  • 1 large egg yolk
  • 1 teaspoon vanilla extract
  • 3/4 cup granulated sugar
  • 3/4 cup all-purpose flour
  • 1/2 teaspoon salt
  • 1/4 cup semi-sweet chocolate chips
  • 1 cup mini marshmallows - (I do a heaping 1 cup!)
  • 1/3 cup marshmallow fluff (cream)

Instructions
 

  • Adjust oven rack to middle position. Preheat oven to 350°F. 
  • Line a 8×8 inch pan with parchment paper, leaving a small overhang on all sides so that you can easily remove the brownies. Spray the parchment with nonstick cooking spray.
  • In a large bowl whisk the boiling water and cocoa powder until smooth. Add the dark chocolate and whisk until the chocolate is melted. Next, whisk in the butter and oil. (Mixture might look clumpy and curdled, that's ok). 
  • Whisk in the egg, egg yolk, and vanilla, stirring until smooth. 
  • Whisk in the sugar until thoroughly combined. Using a spatula fold in the flour, salt, chocolate chips, and mini marshmallows. Do not overmix. 
  • Transfer the batter to the prepared pan. Spread the batter into an even layer in the pan.
  • Place the marshmallow cream in a microwave safe bowl. Heat for 10-15 seconds. Dollop the fluff along the top of the brownie batter. Use a knife to swirl the fluff into the batter. 
  •  Bake for 28-30 minutes or until a toothpick inserted in the center comes out with a few moist crumbs. Be careful not to overbake as this makes brownies dry. 
  • Remove pan from the oven and place on a wire rack to cool completely. (about 1 ½ hours).
  • When ready to serve, lift the parchment overhand and cut the brownies on a cutting board. Enjoy! 

Notes

These brownies can be made several hours ahead of time. Once brownies have cooled, store them in an airtight container at room temperature for 3-4 days.
To freeze, wrap cooled brownies in plastic wrap, place in an airtight container, and freeze for up to two months. Thaw them in the refrigerator, then allow them to come to room temperature.

Nutrition

Calories: 153kcal (8%)Carbohydrates: 19g (6%)Protein: 2g (4%)Fat: 8g (12%)Saturated Fat: 3g (15%)Polyunsaturated Fat: 3gMonounsaturated Fat: 2gTrans Fat: 0.1gCholesterol: 27mg (9%)Sodium: 79mg (3%)Potassium: 53mg (2%)Fiber: 1g (4%)Sugar: 13g (14%)Vitamin A: 78IU (2%)Calcium: 9mg (1%)Iron: 1mg (6%)
Course: Dessert
Cuisine: American
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