Easy Mississippi Mud Brownies Recipe(Marshmallow Brownies) have a soft brownie bottom, gooey marshmallows, and an irresistible chocolate frosting on top.
In a large bowl, beat melted butter, cocoa, milk, and vanilla with 2 cups of powdered sugar.Pour in the rest of the powdered sugar mix until the frosting is ready. It will be light and fluffy, with no lumps.