Description
Mississippi Mud Pie Brownies are rich, fudgy brownies layered with melted chocolate chunks and gooey mini marshmallows, topped with a luscious chocolate cocoa icing. This indulgent dessert combines deep chocolate flavor with a chewy marshmallow topping and smooth, creamy frosting, perfect for chocolate lovers and party treats alike.
Ingredients
Scale
Brownie Base
- 1 cup unsalted butter (227g, Kerrygold recommended)
- 2½ cups granulated sugar (500g, Domino recommended)
- 2 tablespoons canola oil
- 1 tablespoon vanilla extract
- 5 large eggs (Vital Farms recommended)
- 1 cup all-purpose flour (130g, King Arthur recommended)
- ¾ cup + 1 tablespoon Dutch-process cocoa powder (80g, Ghirardelli recommended)
- ¾ teaspoon salt
- 8 ounces dark or milk chocolate (Trader Joe’s Pound of Chocolate recommended)
Topping
- 6 cups mini marshmallows (270g)
Cocoa Icing
- 6 tablespoons salted butter (84g)
- 2½ cups powdered sugar (288g)
- 2 tablespoons unsweetened cocoa powder
- ¼ cup whole milk
- 2 teaspoons vanilla extract
Instructions
- Prepare the Pan: Preheat your oven to 350°F (175°C). Line a 9×13-inch metal cake pan with parchment paper, ensuring some parchment hangs over the edges for easy lift-out after baking. Lightly spray with cooking spray to prevent sticking.
- Melt Butter and Sugar: In a heavy-bottomed saucepan over low heat, melt 1 cup of unsalted butter. Add 2½ cups of granulated sugar and stir until smooth and emulsified, with no separation between butter and sugar. Remove from heat and cool for 5 minutes while stirring frequently to release heat.
- Add Oil and Vanilla: Stir in 2 tablespoons of canola oil and 1 tablespoon of vanilla extract, beating well with a rubber spatula until the mixture is fully combined with no separation.
- Incorporate Eggs: Add 5 large eggs one at a time, mixing thoroughly after each addition with a spatula or fork until fully integrated.
- Add Dry Ingredients: Sift together 1 cup all-purpose flour, ¾ cup plus 1 tablespoon Dutch-process cocoa powder, and ¾ teaspoon salt. Gently fold these dry ingredients into the wet mixture using a rubber spatula until no dry streaks remain.
- Fold in Chocolate Chunks: Chop most of the 8 ounces of dark or milk chocolate into chunks and fold them carefully into the batter.
- Bake Brownies: Pour the batter into the prepared pan, smoothing the top. Sprinkle remaining chocolate chunks evenly over the batter’s surface. Bake for 25 minutes.
- Add Marshmallows and Continue Baking: Remove the brownies from the oven and evenly scatter 6 cups of mini marshmallows over the top. Return to the oven and bake for an additional 3 minutes, allowing marshmallows to melt slightly.
- Remove and Cool: Take the brownies out of the oven and let them cool for a few minutes as you prepare the icing.
- Prepare Cocoa Icing: In a saucepan over medium heat, melt 6 tablespoons salted butter. Remove from heat.
- Add Sugar and Cocoa: Sift in 2½ cups powdered sugar and 2 tablespoons unsweetened cocoa powder, whisking until smooth.
- Add Milk and Vanilla: Whisk in ¼ cup whole milk and 2 teaspoons vanilla extract until the icing is well combined and glossy.
- Ice the Brownies: Immediately pour the icing over the warm marshmallows, spreading evenly with a rubber spatula before it sets quickly.
- Set and Serve: Let the icing set completely before attempting to remove brownies from the pan. For clean cuts, use a plastic knife as metal knives may stick to marshmallows unless treated with nonstick spray and wiped clean.
Notes
- Using parchment paper with overhang ensures easy removal of the brownies from the pan without cracking.
- Cooling the butter and sugar mixture slightly before adding eggs prevents the eggs from cooking during mixing.
- Folding rather than stirring maintains a fudgy brownie texture.
- Freshly chopping chocolate chunks results in better melting and flavor distribution than using chips.
- For clean slicing, allow the icing to fully set and use a plastic knife to avoid marshmallow sticking.
- You can substitute dark chocolate with milk chocolate for a milder sweetness.
- Be cautious when melting butter over low heat to prevent burning.
