Marshmallow Brownies

Marshmallow Brownies are the kind of dessert that looks over-the-top on the pan and completely irresistible on the plate. They start with a rich, fudgy brownie base, get topped with a gooey layer of mini marshmallows, and are finished with a shiny chocolate frosting that sets into a soft, sliceable layer on top. Every bite gives you three textures at once: dense brownie, stretchy marshmallow, and creamy chocolate icing.​

If you’ve ever felt that plain brownies are a little too simple for a special occasion, these Marshmallow Brownies are the answer. They feel like a bakery treat, but they’re easy enough to make on a weeknight with basic pantry ingredients. The method also follows the most successful recipes from big baking blogs: bake the brownies, add marshmallows while they’re still hot so they puff and soften, then cover everything with a quick stovetop or microwave frosting.​

Why you’ll love this recipe

• Fudgy, not cakey: The batter uses melted butter, chocolate, and a relatively low amount of flour, which keeps the brownies dense and fudgy instead of dry.​
• Gooey marshmallow layer: Mini marshmallows go on top of the hot brownies and puff in just a couple of minutes in the oven, giving you that gooey, stretchy layer people love.​
• Quick chocolate frosting: A simple mix of butter, cocoa powder, powdered sugar, and milk makes a glossy frosting that sets as it cools but stays soft when you bite into it.​
• Perfect for parties: This 8×8 pan makes 16 rich squares that are ideal for bake sales, potlucks, holidays, and kids’ birthdays. You can easily double the recipe for a 9×13 pan.​
• Easy to customize: You can add chocolate chips, nuts, or sprinkles, or turn them into “Mississippi mud brownies” by swirling the top slightly instead of smoothing it completely.​

Ingredients

This recipe is inspired by several highly-rated Marshmallow Brownies from popular baking blogs that all follow the same structure: fudgy brownie, mini marshmallows, and a quick cocoa frosting.​

For the brownies (8×8 pan):​

• 1/2 cup (113 g) unsalted butter
• 6 oz (170 g) semi-sweet chocolate chips (about 1 heaping cup)
• 1 cup (200 g) granulated sugar
• 3 large eggs
• 1 teaspoon vanilla extract
• 1/2 cup (63 g) all-purpose flour
• 1/4 cup (22 g) unsweetened cocoa powder
• 1/2 teaspoon fine salt

For the marshmallow layer:​

• 2 cups (about 100 g) mini marshmallows (or enough to cover the surface in a single layer)

For the chocolate frosting:​

• 1/4 cup (57 g) unsalted butter
• 1/4 cup (21 g) unsweetened cocoa powder
• 1 3/4 to 2 cups (210–240 g) powdered sugar
• 3 tablespoons milk, plus more as needed
• 1 teaspoon vanilla extract (optional)

Step-by-step instructions

1. Prepare the pan and oven
   Preheat the oven to 350°F (175°C). Line an 8×8 inch (20×20 cm) baking pan with parchment paper or lightly grease it, making sure you can lift the brownies out easily after baking.​
2. Melt the butter and chocolate
   In a microwave-safe bowl, combine the 1/2 cup butter and 6 oz chocolate chips. Microwave in 30-second bursts, stirring between each, until the chocolate is fully melted and smooth (about 90 seconds total). Let the mixture cool for 2 minutes so it’s warm but not hot.​
3. Whip the eggs and sugar
   In a medium mixing bowl, add the 1 cup sugar and 3 large eggs. Use a hand mixer or stand mixer on high speed to whip for about 3 minutes, until the mixture is thickened, lighter in color, and slightly foamy. This step helps create that shiny, crackly top.​
4. Combine the wet ingredients
   Pour the melted chocolate mixture into the egg mixture and gently fold with a spatula until fully combined. Add the vanilla extract and stir again.​
5. Add the dry ingredients
   Sift or whisk together the flour, cocoa powder, and salt in a small bowl. Add this mixture to the wet ingredients and fold just until no dry streaks remain. The batter will be thick and glossy; avoid overmixing.​
6. Bake the brownie base
   Spread the batter evenly into the prepared pan, smoothing the top with a spatula. Bake for 24–28 minutes, or until the top looks set and a toothpick inserted near the center comes out with moist crumbs but no wet batter.​
7. Add the marshmallows
   Remove the brownies from the oven and immediately sprinkle the mini marshmallows in an even layer over the hot surface. Return the pan to the oven for 2–3 minutes, just until the marshmallows puff and start to lightly brown. Watch closely—marshmallows can burn quickly.​
8. Make the chocolate frosting
   While the marshmallows are puffing or right after, prepare the frosting. In a medium microwave-safe bowl or small saucepan, melt the 1/4 cup butter. Whisk in the 1/4 cup cocoa powder until smooth and no lumps remain. Add 1 3/4 cups powdered sugar and 3 tablespoons milk, then whisk until smooth, thick, and pourable. If needed, add a splash more milk or a little more powdered sugar to reach a frosting that will spread easily but not run off the brownies. Stir in vanilla if using.​
9. Frost the marshmallow layer
   Take the pan out of the oven and, while both the marshmallows and frosting are still warm, immediately pour the frosting over the marshmallow layer. Use an offset spatula or the back of a spoon to gently spread it to the edges, coating all of the marshmallows. It’s okay if some marshmallows peek through; that gives a nice “Mississippi mud” look.​
10. Cool and slice
    Let the brownies cool completely at room temperature until the frosting is set, 1–2 hours. For extra neat slices, you can chill the pan briefly in the fridge before cutting. Lift the brownies out using the parchment, then slice into 16 squares.

Tips, variations, and storage

• Don’t overbake: For fudgy brownies, pull them out when the center still has moist crumbs on a toothpick. Remember they go back in for a couple of minutes with the marshmallows.​
• Use mini marshmallows: They melt and puff evenly; large marshmallows are harder to cut and frost. If you only have large ones, cut them into quarters.​
• Extra chocolate: Stir 1/2 cup chocolate chips into the brownie batter for even more gooey pockets.​
• Make them “Mississippi mud” style: After the marshmallows and frosting go on, lightly swirl the top with a spatula instead of smoothing it completely for a more rustic, muddy look.​
• Storage: Store the brownies in an airtight container at room temperature for up to 3 days, or in the fridge for a firmer texture. They also freeze well, tightly wrapped, for up to 2 months.

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