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Mississippi mud brownies - Image 3

Mississippi Mud Brownies

These legendary Mississippi mud brownies feature a dense, fudgy chocolate base, a melted marshmallow layer, and a silky chocolate frosting. They're incredibly rich, satisfying, and surprisingly simple to make with one bowl.
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Prep Time 20 minutes
Cook Time 35 minutes
Total Time 55 minutes
Servings: 16 servings
Course: Dessert
Cuisine: American
Calories: 450
Ingredients Equipment Method Notes

Ingredients
  

  • 1 cup Unsalted butter melted and slightly cooled
  • 2 cups Granulated sugar
  • 4 large Eggs room temperature
  • 2 tsp Pure vanilla extract
  • 1 cup All-purpose flour spooned and leveled
  • 3/4 cup Unsweetened cocoa powder natural or Dutch-process, sifted
  • 1/2 tsp Salt
  • 1 10.5 oz bag Mini marshmallows about 5-6 cups
  • 1/2 cup Unsalted butter
  • 1/3 cup Whole milk or evaporated milk for extra richness
  • 1/4 cup Unsweetened cocoa powder sifted
  • 1 16 oz box Powdered sugar sifted
  • 1 tsp Pure vanilla extract
  • 1/8 tsp Salt

Equipment

  • 9x13 inch metal baking pan
  • Parchment paper
  • Large mixing bowl
  • Whisk and rubber spatula
  • Medium saucepan
  • Fine-mesh sieve (for sifting)
  • Wire cooling rack

Method
 

  1. Preheat your oven to 350°F (175°C). Grease a 9x13-inch metal baking pan and line it with parchment paper, leaving an overhang on the two long sides. This is your lifeline for clean removal later. In a large bowl, whisk together the melted butter and granulated sugar until combined. Whisk in the eggs, one at a time, followed by the vanilla. The mixture should be smooth and slightly thickened.
  2. Sift the flour, 3/4 cup cocoa powder, and 1/2 teaspoon salt directly into the wet ingredients. Using a rubber spatula, fold the dry ingredients into the wet until just combined and no dry streaks remain. Trust me, overmixing is the enemy of a fudgy texture. The batter will be very thick and glossy.
  3. Spread the thick brownie batter evenly into your prepared pan. It will be a thin layer—this is correct. Bake for 20-25 minutes, or until the top looks set and a toothpick inserted into the center comes out with a few moist crumbs, not wet batter. The edges may just begin to pull away from the pan.
  4. Immediately after removing the pan from the oven, evenly sprinkle the entire surface with the mini marshmallows. Return the pan to the oven for 3-4 minutes, just until the marshmallows are puffed and softened. They will not melt completely, which is perfect. Place the pan on a wire rack and let it cool completely. The marshmallow layer will deflate and become wonderfully gooey as it cools.
  5. While the base cools, make the frosting. In a medium saucepan over medium-low heat, melt the 1/2 cup butter with the milk and 1/4 cup cocoa powder, whisking constantly until smooth and just beginning to simmer. Remove from heat. Whisk in the sifted powdered sugar, vanilla, and salt until completely smooth and pourable. Let it cool for 5 minutes to thicken slightly, then pour evenly over the cooled marshmallow layer. Tip from me: pour from the center and gently tilt the pan to spread—don't stir the marshmallows. Let the frosting set for at least 1 hour before slicing with a hot, wet knife for clean cuts.

Notes

Chef's Tips:
• For clean slices, use a hot knife: run your knife under very hot water, wipe dry, and cut. Repeat between each cut.
• Do not overbake the brownie base. A fudgy, slightly underdone center is key to the classic 'mud' texture.
• Serve at room temperature for the best texture and flavor. These are incredibly rich, so small squares are perfect.
Food Safety:
• Ensure eggs are cooked; the brownie is done when a toothpick shows moist crumbs, not wet batter.
• Store cooled brownies in an airtight container at room temperature for 3-4 days or refrigerate.