These thick, fudgy Marshmallow Swirl Brownies pack layers of deep chocolate flavor, a gooey marshmallow center, and crumbled brownie pieces on top. The first time I pulled these from the oven, the Marshmallow Swirl Brownies were still bubbling and golden, and I knew I'd found something special. They're surprisingly easy to make with just one bowl and no mixer, but they look and taste like something from a fancy bakery.
If you love Easy Italian Love Cake: Addictive, Creamy, and Decadent Dessert with a little extra drama, or you're searching for Easy French Chocolate Flan - Classic Custard Dessert Made that wow a crowd, these are about to become your new favorite. They're also perfect alongside Easy Decadent Biscoff Icebox Cake Recipe - No-Bake, Quick & Irresistible when you need a dessert spread that feels warm and indulgent.
Why You'll Love This Recipe
These chocolate Marshmallow Swirl Brownies deliver everything you want in a dessert without any fuss. The batter comes together in one bowl with just a whisk, so there's no stand mixer to drag out or extra dishes to wash. The texture is incredibly fudgy, almost truffle-like in the center, with edges that bake up just slightly crisp. That gooey marshmallow layer adds sweetness and a fun, stretchy pull when you take a bite.
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Marshmallow Swirl Brownies Ingredients
Here's what you'll need to make these fudgy brownies with a Marshmallow Swirl Brownies twist.
See Recipe Card Below This Post For ingredients Quantites
Butter: Melted butter creates the rich, dense texture that makes these brownies so fudgy. You can use regular or dairy-free butter without changing the recipe.
Granulated sugar: Adds sweetness and helps create that shiny, crackly top layer.
Light brown sugar: Brings moisture and a hint of caramel flavor that balances the cocoa.
Vanilla extract: Deepens the chocolate flavor and adds warmth.
Eggs: Bind everything together and give the brownies structure without making them cakey.
All-purpose flour: Provides just enough structure to hold the layers together while keeping the texture soft.
Unsweetened Dutch processed cocoa powder: This is what makes the brownies intensely chocolatey and fudgy. Dutch processed cocoa gives a smoother, less acidic flavor.
Salt: Balances the sweetness and makes the chocolate taste even richer.
Mini chocolate chips: Sprinkled on top, they melt slightly and add little bursts of chocolate throughout.
Mini marshmallows: These create the gooey, stretchy middle layer. Mini Marshmallow Swirl Brownies melt more evenly than large ones.
how to make Marshmallow Swirl Brownies
Prepare the pans: Line an 8×8-inch square baking pan with parchment paper, letting the edges hang over the sides so you can lift the brownies out easily later. Line a second smaller pan (either 9×5 or 8×4 loaf pan) with parchment paper as well. Preheat your oven to 350°F.
Mix butter and sugars: Melt the butter in a large microwave-safe bowl or in a saucepan on the stove. Add both sugars and whisk everything together until the mixture thickens up and starts to pull away from the sides of the bowl. It should look like a thick, glossy paste.
Add eggs and vanilla: Whisk in the eggs and vanilla extract, mixing until the batter looks smooth and well combined.
Incorporate dry ingredients: Add the flour, cocoa powder, and salt all at once. Whisk gently just until you don't see any dry streaks. Don't over-mix, or the brownies might turn out tough.
Divide and bake batter: Pour about two-thirds of the batter into the prepared square pan, spreading it evenly. Pour the remaining third into the loaf pan. Bake both pans at the same time for 27 to 36 minutes, checking with a toothpick. You want a few wet crumbs clinging to it, not a clean toothpick.
Add marshmallow layer: Take both pans out of the oven but leave the oven on. Sprinkle the mini marshmallows evenly over the brownies in the square pan. Put that pan back in the oven and bake for another 4 to 8 minutes, just until the Marshmallow Swirl Brownies puff up, turn gooey, and start to brown lightly on top.
Crumble extra brownies: While the Marshmallow Swirl Brownies are baking, use a spoon to break up the loaf pan brownies into small, irregular chunks. They'll still be warm, so this is easy.
Finish the topping: Pull the Marshmallow Swirl Brownies from the oven. Sprinkle the crumbled brownie pieces all over the marshmallow layer, pressing them in gently so they stick. Finish by scattering the chocolate chips evenly on top.
Cool and slice: Let the brownies cool completely in the pan before using the parchment overhang to lift them out. Slice into 16 squares with a sharp knife, wiping the blade between cuts for clean edges.
Substitutions and Variations
You can adjust this easy brownie recipe to fit your pantry or preferences.
Dairy-free version: Use dairy-free butter and dairy-free chocolate chips. The texture stays the same.
Dark chocolate boost: Fold in ½ cup of chopped dark chocolate along with the mini chips for even more chocolate intensity.
Peanut butter swirl: Drop spoonfuls of peanut butter over the Marshmallow Swirl Brownies layer before adding the crumbled brownies. Swirl gently with a knife.
Nutty crunch: Add ½ cup of chopped walnuts or pecans to the batter before baking, or sprinkle them on top with the chocolate chips.
Fluffier marshmallows: If you prefer a taller Marshmallow Swirl Brownies layer, use 4 cups of mini marshmallows instead of 3½ cups.
Sea salt finish: Sprinkle flaky sea salt over the top right after baking for a sweet and salty contrast.
Equipment For Marshmallow Swirl Brownies
Here's what makes this recipe come together easily.
8×8 inch square baking pan: This is your main pan for the layered brownies.
9×5 or 8×4 loaf pan: You'll bake the extra brownie batter here to crumble on top later.
Parchment paper: Lining both pans makes it easy to lift out the brownies and keeps cleanup simple.
Large microwave-safe bowl: For melting the butter and mixing the batter. You can also use a saucepan if you prefer stovetop melting.
Whisk: A simple whisk is all you need to mix the batter smoothly.
Spoon: For crumbling the loaf pan brownies and spreading the batter.
Storage and Make-Ahead Tips
These brownie bars keep well and actually taste even fudgier the next day.
Room temperature: Store brownies in an airtight container at room temperature for up to 3 days. The Marshmallow Swirl Brownies layer stays soft and gooey.
Refrigerator: Keep them in the fridge for up to a week. They'll firm up slightly when cold, which some people prefer. Let them sit at room temperature for 10 minutes before serving if you want them softer.
Freezer: Wrap individual brownies in plastic wrap, then place them in a freezer bag. Freeze for up to 3 months. Thaw at room temperature or warm in the microwave for 15 seconds.
Make-ahead: You can bake the brownies a day ahead and store them covered at room temperature. They slice more cleanly when fully cooled.
Expert tips
Don't over-bake: Pull the brownies when a toothpick comes out with wet crumbs, not clean. They'll continue cooking slightly as they cool, and this keeps them fudgy instead of cakey.
Use room-temperature eggs: Cold eggs can seize up the melted butter. Let your eggs sit out for 15 minutes before mixing.
Line the pans well: Make sure your parchment paper hangs over the edges. This makes lifting the brownies out so much easier and prevents them from breaking.
Watch the marshmallows closely: They can go from perfectly golden to burnt quickly. Check them after 4 minutes and pull them as soon as they're puffy and lightly browned.
Let them cool completely: I know it's hard to wait, but warm brownies are difficult to slice cleanly. Cooling them fully gives you those perfect, Instagram-worthy squares.
Wipe your knife: Clean the knife between cuts to keep the edges sharp and prevent Marshmallow Swirl Brownies from smearing.
FAQ
What is a Mississippi brownie?
A Mississippi brownie is a layered dessert that typically includes a brownie base, a Marshmallow Swirl Brownies layer, and sometimes a chocolate frosting or peanut butter topping. It's similar to Mississippi Mud Pie but in brownie form. These Marshmallow Swirl Brownies follow that same layered concept with a crumbled brownie topping instead of frosting.
How to add swirl to brownies?
To create a swirl effect, drop spoonfuls of a contrasting ingredient (like cream cheese, peanut butter, or caramel) over the brownie batter before baking. Use a knife or skewer to gently drag through the drops in a figure-eight pattern. For Marshmallow Swirl Brownies swirls specifically, you can partially melt marshmallows on top and swirl them with a knife before they fully set.
What is the difference between blondies and brownies?
Brownies are chocolate-based bars made with cocoa powder or melted chocolate, giving them a rich, dark color and deep chocolate flavor. Blondies are made without cocoa, using brown sugar and butter to create a butterscotch or vanilla flavor with a golden color. Both have a dense, chewy texture, but the main difference is the presence of chocolate.
Can I add marshmallow fluff to my brownie mix?
Yes, you can swirl Marshmallow Swirl Brownies fluff into brownie batter before baking. Drop spoonfuls on top of the batter and swirl gently with a knife. Keep in mind that marshmallow fluff doesn't create the same gooey, melted layer as mini marshmallows do. For the best texture, use actual marshmallows that can puff and caramelize in the oven.
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Marshmallow Swirl Brownies
Ingredients
Method
- Line an 8×8-inch pan with parchment paper, leaving excess over the sides, and line a loaf pan separately, then preheat the oven to 350°F. prep
- Melt the butter in a heat-safe bowl, then whisk in both sugars until the mixture thickens and pulls slightly from the sides. mix
- Stir in the eggs and vanilla until glossy, then gently whisk in the flour, cocoa powder, and salt just until combined. mix
- Spread about two-thirds of the batter into the square pan and transfer the remaining batter to the loaf pan, then bake both pans together until a toothpick shows moist crumbs. bake
- Remove both pans while keeping the oven on, scatter marshmallows over the square pan brownies, and return them to the oven briefly until the marshmallows puff and soften. bake
- Break the loaf pan brownies into bite-size chunks while still warm, then remove the marshmallow pan and scatter the brownie pieces over the top, pressing lightly and finishing with chocolate chips. assemble
- Allow the brownies to cool fully before lifting them out and slicing into squares. finish
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