The only thing better than brownies is marshmallow and pecan filled brownies covered in chocolate icing. I love my Mississippi Mud Brownies because my home state is in the name and they remind me of home.
Technique tip: Line the baking dish with tin foil; it makes it much easier to lift out the brownies.
Swap option: Feel free to use walnuts or almonds instead of pecans if you prefer.
For the Mississippi mud brownies:
Preheat oven to 325°F. Line an 8- by 8-inch square baking dish with aluminum foil and lightly coat with non-stick cooking spray.
In a large bowl, whisk together the flour, cocoa powder, granulated sugar, brown sugar and salt until blended. Using a wooden spoon stir in the melted butter and mix until combined. The batter may get hard like fudge at this point. Add the eggs and vanilla extract and stir until blended and no clumps remain. Fold in 1/2 cup of the chopped pecans.
Pour the batter into the prepared baking dish and bake for 35 to 37 minutes or until a thin knife or skewer inserted into the center comes out with very moist crumbs attached. Remove from the oven and sprinkle the marshmallows evenly over the top. Return the pan to the oven and bake until the marshmallows are slightly puffy, about 4 minutes.
Remove from oven and place on a wire cooling rack. Allow the brownies to rest for 5 minutes.
For the icing:
In a small saucepan, melt the butter over medium-high heat, stirring frequently. Add the milk and cocoa powder and cook, whisking constantly until the mixture has thickened, about 1–2 minutes.
Remove from the heat and add the powdered sugar, vanilla and salt. Beat with an electric mixer on medium speed until the frosting is smooth.
Immediately pour and spread the chocolate icing evenly over top of the brownies (work quickly as the icing begins to harden as soon as its made). Sprinkle the top with remaining chopped pecans. Allow them to cool completely, then cut into squares.
The brownies can be stored in an airtight container at room temperature for up to 5 days.