Marshmallow Brownies

These gooey marshmallow brownies are the kind of indulgence that brings pure joy with every bite. They're rich, deeply chocolatey, and swirled with ribbons of soft marshmallow fluff that melt into the fudgy layers. Perfectly chewy around the edges and ultra-soft in the center, they offer that irresistible contrast that chocolate lovers crave. Think of them as a cozy treat that satisfies like a s'more—minus the graham crackers and the campfire.

When I made these for the first time, I was stunned by how that marshmallow swirl turned golden and slightly crisp while staying fluffy inside. My family couldn't get enough—these disappeared before they even cooled completely. It's a recipe I return to every time I need that chocolate-marshmallow comfort.

Pantry Picks That Matter

• Large eggs and yolk: Using cold eggs helps whip them into a thick, pale foam that gives brownies their signature glossy top. The extra yolk makes them even richer.
• Unsalted butter: Melted and slightly cooled, it brings moisture and deep flavor to the base. Always go for real butter, not margarine.
• Oil: A bit of canola or vegetable oil adds tenderness. It keeps the brownies moist for days.
• Dutch-process cocoa powder: For that bold chocolate flavor, I recommend dutch-process. It's smoother and richer than regular cocoa.
• Cornstarch: This small addition softens the texture and ensures that melt-in-your-mouth bite.
• Semisweet chocolate chips: These melt into little pools inside the brownie. I skip milk chocolate—it's too sweet with the fluff.
• Marshmallow fluff: Whether labeled "fluff" or "crème," this sticky swirl bakes into pockets of sweet magic. Choose a quality one without too many additives.

Building That Batter

Dry Mix Ready:

In a medium bowl, sift together the flour, cocoa powder, and cornstarch to remove lumps and ensure even mixing. Add a pinch of salt to balance the sweetness and enhance flavor depth.

Whipping the Eggs:

In a large mixing bowl, combine granulated sugar, whole eggs, and one extra yolk. Beat on high speed for 5 full minutes until the mixture turns pale, thick, and airy. This step helps form the delicate crackly top layer once baked.

Pour in the Wet:

Add your cooled melted butter, oil, and vanilla extract to the egg mixture. Mix gently until it turns smooth and glossy. This base is where the rich flavor starts to build.

Combining Everything:

Add your sifted dry ingredients into the wet mixture. Mix just until you see no more flour streaks—avoid overmixing. Fold in the chocolate chips with a spatula so they're evenly spread without deflating the batter.

Marshmallow Swirl:

Pour the batter into a parchment-lined 9x9-inch pan. Add dollops of melted marshmallow fluff across the surface. Drag a butter knife through the dollops in gentle curves to create that beautiful swirl pattern.

Time to Bake:

Place in a preheated oven and bake for 45 to 55 minutes. Check for doneness with a toothpick—it should come out with moist crumbs, not wet batter. Let cool fully on a wire rack to finish setting.

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I especially love the way the marshmallow caramelizes slightly on top. It reminds me of roasted marshmallows at summer bonfires, something my kids now request year-round in these brownies.

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Frequently Asked Questions

→ Can I use regular cocoa powder instead of Dutch process?

Yes, you can use regular unsweetened cocoa powder if that's what you have on hand. Dutch process gives a deeper, darker chocolate flavor, but regular cocoa powder will still make delicious brownies. The color might be slightly lighter and the flavor a bit less intense.

→ My marshmallow topping disappeared into the brownies while baking. What happened?

This can happen if the marshmallow fluff is mixed too deeply into the batter. For a visible swirl, make sure to just lightly drag a knife through the dollops of marshmallow to create a marbled effect without pushing it down into the batter too much.

→ Can I use homemade marshmallow fluff instead of store-bought?

Absolutely! Homemade marshmallow fluff works beautifully in this recipe. If your homemade version is thicker than store-bought, you might need to warm it a bit longer in the microwave to get a good consistency for swirling.

→ How can I tell when the brownies are done without overbaking them?

The toothpick test is perfect for these brownies - insert a toothpick into the center and it should come out with a few moist crumbs attached, but not wet batter. If it comes out completely clean, the brownies might be overbaked. Remember they'll continue to set as they cool.

→ Can I add other mix-ins to these brownies?

Definitely! These brownies are very versatile. You could add chopped nuts, white chocolate chips, or even caramel bits. Just be careful not to add too many mix-ins as this could affect the cooking time and texture of the final product.