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Marshmallow Swirl Brownies

Published on December 16, 2021. Last updated on June 28, 2023. By Gabby. 25 Comments

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These marshmallow brownies are total decadence! A thick layer of fudgy brownie, topped with gooey marshmallows, then topped with more fudgy brownies and chocolate chips! Easy to make and no mixer required!

marshmallow brownies stacked on top of each other with chocolate chips scattered around

I’m just going to say it - I am, in general, not the biggest marshmallow fan. I know - crazy right? Normally, I tend to find marshmallow desserts to be too sweet but holy smokes - these marshmallow swirl brownies are absolute perfection.

Brownies are one of my greatest loves. The base of these brownies is my one bowl brownies, which is one of my favorite recipes ever! The gooey marshmallow layer is baked onto the brownies, then sprinkled with more brownies pieces. To top it all off, we add mini chocolate chips to the warm marshmallow layer so they get soft and meltey!

marshmallow swirl brownies sliced on parchment paper

Why These Marshmallow Swirl Brownies Are The Best

These brownies have been tested both with regular dairy ingredients, and with dairy free ingredients! They can be made either way!
You can easily customize this recipe - if you don’t want to add the brownie layer on top, I’ve provided instructions for making it without them.
If you’re making these around the holiday season, I highly recommend sprinkling crushed candy canes on top, and if you’re making them in the summer, add some crushed up graham crackers over the marshmallow layer to make them into s'mores brownies!
This recipe requires just a few key ingredients and you don’t even need a mixer!

two marshmallow brownies stacked on top of each other

Ingredients Needed

Cocoa Powder: I recommend unsweetened dutch processed cocoa powder works for these brownies, but you can use natural cocoa powder if that's what you have.
Marshmallows: I tested these marshmallow swirl brownies with mini marshmallows and regular sized marshmallows, and mini marshmallows melt the best. Regular sized marshmallows will still work in a pinch. You can also use melted marshmallow fluff if you prefer!
Flour: This recipe uses all purpose flour, and has not been tested with other types of flours.
Butter: You can use regular dairy butter, or dairy free butter in this recipe!

Step By Step Instructions

nutella stuffed cookies process in six steps

STEP ONE: Prepare two pans: the first pan will be an 8x8 inch square baking pan. Line it with parchment paper, leaving some hanging over the sides to make it easier to remove the brownies later. Prepare a second pan, either a 9x5 or 8x4 loaf pan with parchment paper as well. Preheat the oven to 350°F.

STEP TWO: In a large microwave-safe bowl, melt the butter. Add in the brown sugar and white sugar and whisk until the mixture pulls away from the sides of the bowl as you whisk. Whisk in eggs and vanilla extract.

STEP THREE: Add in the flour, salt, and cocoa powder and whisk until combined (do not over mix). Add two thirds of the brownie batter into the prepared 8x8 pan, then add the remaining one third of the batter into the loaf pan. Bake both pans of brownies for 28-36 minutes, or until a toothpick inserted in the middle of each pan comes out with just a few wet crumbs on it.

step by step showing how to make marshmallow swirl brownies

STEP FOUR: When the brownies are ready, remove both pans from the oven, leaving the oven on. Set the loaf pan aside. Pour the mini marshmallows on top of the larger 8x8 pan of brownies, then place it back in the oven for 4-8 minutes, or until the marshmallows are gooey and the tops have started to turn golden brown. Meanwhile, use a spoon to break up the brownies in the loaf pan into chunks or small pieces.

STEP FIVE: Remove the brownies from the oven. Scoop out small chunks of brownie from the loaf pan and sprinkle over top of the marshmallow layer.

You can use your hands to do this if the brownies have cooled enough. Sprinkle all the crumbled up brownie over top of the marshmallows then sprinkle with more chocolate chips.

step by step showing how to make marshmallow brownies

Fun Flavor Ideas!

There are a few super fun ways I like to make these marshmallow brownies even MORE extra than they already are, so I’m sharing a few below. Go big or go home right?!

Peppermint Brownies: If you are making these brownies around Christmas and the holiday season, make them into candy cane marshmallow brownies! Add ½ teaspoon of peppermint extract to the brownie batter if desired, or just sprinkle crushed candy canes over the warm marshmallows!
S’mores Brownies: If you’re a s’mores lover, sprinkle some chopped or crushed up graham crackers over the marshmallows along with the chocolate chips and crumbled up brownie chunks!
Fluffernutter Brownies: Drizzle melted peanut butter over top of the melted marshmallows to make these into peanut butter marshmallow brownies!

three marshmallow brownies stacked on top of each other with candy cane pieces scattered around

FAQs and Expert Tips

Can I make these brownies using marshmallow fluff?

Yes! If you’d rather use marshmallow fluff instead of mini marshmallows, heat 2 cups of marshmallow fluff for 15-20 seconds or until melted and pourable. Pour over top of the brownies, then sprinkle the crumbled brownies and chocolate chips over top.

Can I make marshmallow swirl brownies using large marshmallows?

In a pinch, they will work, but I highly recommend mini marshmallows. They melt easier and spread out more evenly than large marshmallows.

Can I make these brownies without the extra brownie pieces on top?

Yes you can! You do this two ways. You can make the brownie recipe as is, then bake it all in one pan. This will give you an extra thick brownie layer, and the brownies will take longer to bake. Alternatively, you can use this brownie recipe as the base layer.

Can I add more marshmallows?

Yes! To make the marshmallow layer even thicker you can add an extra half cup of mini marshmallows on top of the brownies.

three marshmallow swirl brownies stacked on top of each other with marshmallows scattered around

Expert Tips

Don’t skip the parchment paper lining in the pans! It will be more difficult to remove the brownies from the pan to slice them if you skip this step.
Properly measure your flour and cocoa powder - If you over-measure your flour or cocoa powder, the brownies won't be as fudgy and gooey! I strongly recommend weighing both ingredients with a kitchen scale or using the scoop and level method.
Don't over-mix - The texture of brownies can be affected by over-mixing, so be careful to only whisk until the dry ingredients have been incorporated.
Watch the bake time! Since you are baking two pans at once, you’ll want to be extra cautious of baking time. Over-baking your brownies will lead to tough brownies. Start checking on both pans early. The toothpick shouldn’t be completely clean when they come out, but shouldn’t be covered in batter. A few wet crumbs means they are done.
Gently push the brownie pieces into the warm marshmallow layer to help them stay in place and create more of a layer of brownie on top.
Resist the urge to slice the brownies while they’re warm. Because the brownies are super fudgy, and the marshmallows are hot and gooey, they need some time to set and firm up first.

Storage and Freezing Instructions

These brownies can be stored un-sliced in the baking pan covered tightly with tin foil, or sliced in an airtight container at room temperature for up to 5 days.

More Brownies and Bars You'll Love

If you make this recipe, let me know how it went in the comments below, I’d love to hear from you! You can also tag me on Instagram or Facebook so I can check it out!

The calorie information provided for this recipe is an estimate. The accuracy of the calories listed is not guaranteed.

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