Description
Mississippi Mud Pie Brownies are a decadently rich chocolate dessert featuring a fudgy brownie base loaded with dark chocolate chunks, topped with a gooey layer of mini marshmallows and finished with a smooth, chocolate cocoa icing. These brownies offer a perfect balance of intense chocolate flavor and a delightful marshmallow topping, ideal for chocolate lovers seeking an indulgent treat for gatherings or special occasions.
Ingredients
Scale
Brownie Batter
- 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 (preferably half a Trader Joe’s Pound of Chocolate bar)
- 6 cups mini marshmallows (270g)
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
- Preheat and prepare pan: Preheat your oven to 350°F (177°C). Line a metal 9×13-inch cake pan with parchment paper, making sure some parchment hangs over the edges for easy removal later. Use two sheets if necessary, placing the shorter sheet underneath the longer one along the pan’s length. Lightly spray the parchment with cooking spray.
- Melt butter and mix sugar: In a heavy-bottomed saucepan over low heat, melt 1 cup unsalted butter. Stir in 2½ cups granulated sugar until the mixture is smooth and starting to emulsify without any separated butter. Remove from heat and let cool for 5 minutes, stirring frequently to dissipate heat.
- Add oil and vanilla: Stir in 2 tablespoons canola oil and 1 tablespoon vanilla extract using a rubber spatula until fully combined with no visible separation.
- Incorporate eggs: Beat in 5 large eggs one at a time, thoroughly mixing after each addition with a spatula or fork until fully incorporated.
- Add dry ingredients: Sift together 1 cup all-purpose flour, ¾ cup plus 1 tablespoon Dutch-process cocoa powder, and ¾ teaspoon salt. Gently stir the sifted dry ingredients into the wet mixture with a rubber spatula just until no dry streaks remain.
- Mix in chocolate chunks: Fold most of the 8 ounces dark or milk chocolate chunks into the batter, reserving some to sprinkle on top.
- Bake initial layer: Pour the brownie batter into the prepared pan, then evenly sprinkle the remaining chocolate chunks on top. Bake in the preheated oven for 25 minutes.
- Add marshmallows and continue baking: Remove the pan from the oven and evenly scatter 6 cups mini marshmallows over the top. Return the pan to the oven and bake for an additional 3 minutes until marshmallows begin to melt and puff.
- Cool slightly: Take the brownies out and allow them to cool for several minutes to prepare the icing.
- Prepare icing base: In a saucepan over medium heat, melt 6 tablespoons salted butter until fully liquefied.
- Mix icing ingredients: Sift in 2½ cups powdered sugar and 2 tablespoons unsweetened cocoa powder. Whisk until well combined. Then add ¼ cup whole milk and 2 teaspoons vanilla extract, whisking until smooth and glossy.
- Finish icing and top brownies: Remove from heat and immediately pour the icing over the warm marshmallows. Use a rubber spatula to spread the icing evenly. The icing will begin to set quickly.
- Set and serve: Allow the icing to set completely before removing the brownies from the pan. For best and cleanest slicing, use a plastic knife since metal knives can stick to marshmallows unless treated with nonstick spray.
Notes
- Using parchment paper with overhanging edges makes it easy to lift the brownies out of the pan for cutting and serving.
- Allow the butter and sugar mixture to cool slightly before adding eggs to prevent cooking them and achieve a smooth batter.
- The Dutch-process cocoa powder provides a rich chocolate flavor and darker color.
- Folding in chocolate chunks adds delightful pockets of melted chocolate within the brownies.
- Using mini marshmallows allows for even coverage and a gooey topping layer.
- For smooth icing, make sure to sift powdered sugar and cocoa powder before whisking.
- The icing sets quickly once poured; work efficiently to cover the marshmallows evenly.
- Cut brownies with a plastic knife or spray/wipe a metal knife with nonstick spray to prevent marshmallow sticking.
