Description
Mississippi Mud Pie Brownies are a rich and decadent dessert combining fudgy brownie layers with melted marshmallows and a creamy chocolate icing. This indulgent recipe features a buttery, cocoa-infused brownie base studded with chunks of dark or milk chocolate, topped with sticky mini marshmallows and a luscious chocolate cocoa icing. Perfect for special occasions or satisfying sweet tooth cravings, these brownies deliver a delightful combination of textures and intense chocolate flavor.
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 preferred)
- 1 cup all-purpose flour (130g, King Arthur suggested)
- ¾ cup + 1 tablespoon Dutch-process cocoa powder (80g, Ghirardelli preferred)
- ¾ teaspoon salt
- 8 ounces dark or milk chocolate, roughly chopped
Topping
- 6 cups mini marshmallows (270g)
Chocolate 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. Line a 9×13-inch metal cake pan with parchment paper and lightly spray with cooking spray. Overlap two sheets of parchment paper so they cover the pan with extra hanging over the edges for easy removal later.
- Melt Butter and Sugar: Melt 1 cup unsalted butter in a heavy-bottomed saucepan over low heat. Add 2½ cups granulated sugar and stir until the mixture becomes smooth and emulsified with no separation of butter.
- Cool and Combine Flavors: Remove from heat and allow butter and sugar mixture to cool for 5 minutes, stirring often. Then add 2 tablespoons canola oil and 1 tablespoon vanilla extract and beat with a rubber spatula until fully combined and no separation remains.
- Add Eggs: Beat in 5 large eggs one at a time, mixing thoroughly after each addition until all are incorporated.
- Incorporate Dry Ingredients: Sift together 1 cup all-purpose flour, ¾ cup plus 1 tablespoon Dutch-process cocoa powder, and ¾ teaspoon salt. Gently fold the sifted dry ingredients into the wet butter mixture with a rubber spatula until no dry streaks remain.
- Fold in Chocolate Chunks: Fold most of the 8 ounces chopped dark or milk chocolate into the batter, reserving some chunks for topping.
- Bake Brownies: Pour the batter into the prepared pan and sprinkle the remaining chocolate chunks evenly on top. Bake in the oven for 25 minutes.
- Add Marshmallows and Continue Baking: Remove the brownies and evenly sprinkle 6 cups mini marshmallows across the surface. Return to the oven and bake for an additional 3 minutes until marshmallows soften and begin to melt.
- Cool Before Icing: Remove the pan from oven and allow the brownies to cool for a few minutes while preparing the icing.
- Prepare Chocolate Icing: Melt 6 tablespoons salted butter in a saucepan over medium heat. Sift in 2½ cups powdered sugar and 2 tablespoons cocoa powder and whisk until smooth.
- Add Milk and Vanilla to Icing: Whisk in ¼ cup whole milk and 2 teaspoons vanilla extract until fully combined and smooth. Remove from heat immediately.
- Top Brownies with Icing: Pour the warm icing evenly over the marshmallow layer and use a rubber spatula to spread it for full coverage. The icing will begin to set quickly.
- Set and Slice: Allow the icing to set completely before lifting the brownies from the pan using the parchment overhang. Slice into 24 squares using a plastic knife for clean cuts to avoid sticking marshmallows.
Notes
- Using parchment paper with overhang makes removing brownies from the pan easier and cleaner.
- Cool the butter-sugar mixture slightly before adding eggs to prevent curdling.
- Reserve some chocolate chunks to sprinkle on top for additional texture and visual appeal.
- Use a plastic knife to slice brownies for clean cuts; metal knives may cause marshmallows to stick.
- Marshmallows melt quickly during the final bake, so watch carefully to avoid burning.
