
Ultra-fudgy brownies crowned with melty marshmallows and a glossy cocoa icing. A nostalgic crowd-pleaser that slices cleanly and disappears fast.

There are desserts that take you straight back to warm kitchens and busy family gatherings, and these fudgy Mississippi Mud Brownies do exactly that for me. I first made them for a summer potluck when I needed something indulgent, sturdy enough to travel, and guaranteed to delight both kids and adults. That marshmallow layer seals the deal: it melts into a pillowy blanket over the brownies, then gets cloaked in a quick, satiny cocoa icing that sets into a perfect sliceable top. The contrast of textures is irresistible, from the chewy edges to the gooey center and soft marshmallow bite.
I have a soft spot for this version because it leans unapologetically fudgy. Kerrygold unsalted butter brings rich flavor, while Domino sugar dissolves into the butter for that classic shiny top. Dutch-process cocoa (I love Ghirardelli) deepens the chocolate without bitterness, and a handful of chopped chocolate from a Trader Joe’s Pound Plus bar creates pockets of molten goodness. Over the years, these brownies have earned a regular spot in my rotation for birthdays, bake sales, and casual Friday nights. The first slice always goes to the impatient person hovering by the counter—usually me.
When I first brought these to a neighborhood block party, the pan was clean before the burgers hit the grill. My family loves the chewy edges, and my nieces go straight for the marshmallow pockets. Over time, I’ve learned that the icing pour is a small moment of magic—the way it glides over the warm marshmallows, then sets into a glossy cap that slices like a dream.
My favorite moment is guiding the icing across the soft marshmallows and watching it settle into glossy waves. It reminds me of summer bonfires without the smoke—just pure chocolate nostalgia. When my dad tried these, he paused mid-bite and nodded the slow, approving nod that every baker hopes to see. From then on, he started hinting at “that marshmallow brownie” for every family event.
Cool the slab completely before lifting from the pan and slicing. Store squares in a single layer or with parchment between layers in an airtight container at room temperature for 3 to 4 days. For longer storage, freeze on a sheet tray until firm, then transfer to freezer bags with the air pressed out; they keep up to 3 months. To serve, thaw at room temperature 1 to 2 hours. Avoid refrigeration, which can dry the crumb and harden the icing. If you like a slightly warm bite, microwave an individual square for 8 to 10 seconds—just enough to soften the marshmallow again.
If you only have natural cocoa, use the same amount; expect a slightly lighter color and a touch more bitterness. Semi-sweet chips can stand in for chopped chocolate, though chopped bars melt into softer puddles. No canola oil? Use vegetable or light olive oil. Salted butter in the batter is fine—simply reduce added salt to a scant 1/2 teaspoon. For the icing, you can swap 2 to 3 tablespoons of the milk with hot coffee to intensify chocolate flavor. If you must use a glass pan, lower the oven temperature to 325°F and extend bake time by 5 to 8 minutes, checking often.
These are sensational on their own, but a small scoop of vanilla or coffee ice cream sets off the fudgy crumb. For a party platter, cut smaller 1 1/2 inch squares and arrange in a tight grid, then dust lightly with cocoa powder for a bakery look. A drizzle of warm caramel is a fun, sticky twist. In summer, serve with fresh strawberries or raspberries; their tartness balances the sweetness. For a birthday dessert board, add bowls of toasted pecans and crushed pretzels so guests can sprinkle a crunchy finish on their slices.
Mississippi mud sweets trace their roots to Southern kitchens, named for the dense, rippled look that resembles riverbank mud. The classic combination involves a fudgy base, marshmallow blanket, and chocolate icing, though some regions add nuts or swap the brownie for cake. This brownie-forward version leans on the tradition of rich, crowd-pleasing desserts that travel well and slice neatly for gatherings. Over time, the style spread far beyond the South, becoming a potluck staple wherever chocolate lovers congregate. It is a dessert that asks for paper plates, good company, and a second square.
In winter, add 1/2 teaspoon peppermint extract to the icing for a hot-cocoa vibe and sprinkle with crushed candy canes. In spring, swirl 1/4 cup raspberry jam onto the brownie batter before baking for tart ribbons. Summer calls for fresh berry sides and smaller squares. For fall, fold in 3/4 cup toasted pecans and a pinch of cinnamon to the batter for warmth. Holiday parties love a drizzle of salted caramel over the set icing, or a scatter of mini chocolate chips while the icing is still soft.
Bake the brownie base a day ahead, cool, cover, and hold at room temperature. About an hour before serving, rewarm in a 300°F oven for 5 minutes, add marshmallows for 3 minutes, then finish with the icing. To portion for lunchboxes, cut once the icing sets and wrap squares individually in parchment or plastic wrap. For large events, double the recipe and bake in two separate metal pans to ensure even cooking; do not attempt a single thicker pan, which risks underbaking the center.
One of my favorite bake sale memories was watching a hesitant buyer circle the table, choose a square, then come back immediately to purchase three more “just in case.” Another time, I brought a pan to a moving day and it powered an entire crew of friends through the last boxes. These brownies have that rare, reassuring quality: they feel homemade and nostalgic while looking polished and party-ready. Keep this one in your back pocket; it rarely fails to make someone’s day.
If chocolate comfort is what you crave, this pan delivers every time. Bake a batch, share it generously, and enjoy the quiet moment when the glossy icing cracks under your knife and the marshmallow sighs beneath it—that’s the sweet spot.
This Fudgy Mississippi Mud Brownies recipe makes perfectly juicy, tender, and flavorful steak every time! Serve with potatoes and a side salad for an unforgettable dinner in under 30 minutes.

Preheat oven to 350°F. Line a metal 9 by 13 inch pan with parchment, leaving overhang. Lightly coat with cooking spray. Arrange two sheets if needed, with the shorter sheet under the longer for secure lifting.
Melt 1 cup unsalted butter over low heat. Stir in 2 1/2 cups granulated sugar until the mixture is glossy and uniform with no separated butter. Remove from heat and cool 5 minutes, stirring often.
Stir in 2 tablespoons canola oil and 1 tablespoon vanilla. Add 5 large eggs one at a time, mixing thoroughly after each addition until fully incorporated and shiny.
Sift in 1 cup all-purpose flour, 3/4 cup plus 1 tablespoon Dutch-process cocoa, and 3/4 teaspoon salt. Fold gently just until no dry streaks remain.
Fold most of the 8 ounces chopped chocolate into batter. Spread into prepared pan, scatter remaining chocolate on top, and bake 25 minutes until edges are set and center is soft but not liquid.
Remove pan and sprinkle 6 cups mini marshmallows evenly over top. Return to oven for 3 minutes until marshmallows are soft and slightly puffed.
Melt 6 tablespoons salted butter over medium heat. Whisk in 2 1/2 cups powdered sugar and 2 tablespoons cocoa, then whisk in 1/4 cup whole milk and 2 teaspoons vanilla until smooth. Immediately pour over marshmallows. Let set completely before slicing.
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Ultra-fudgy brownies crowned with melty marshmallows and a glossy cocoa icing. A nostalgic crowd-pleaser that slices cleanly and disappears fast.

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This recipe looks amazing! Can't wait to try it.
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