Mississippi Mud Brownies

Mississippi Mud Brownies {a.k.a. The Tim Riggins Brownie}Recipe very lightly adapted from Southern Living Comfort Food
Brownies:1 1/2 c. all-purpose flour2 c. sugar1/2 c. unsweetened cocoa powder2 tsp. baking powder1/2 tsp. table salt1 c. (2 sticks) melted butter (no substitutions)4 eggs, lightly beaten1 Tbsp. vanilla extract1 c. semi-sweet chocolate chips3 c. mini marshmallows (or enough flat marshmallows to cover a 9×13″ pan)
Frosting:1/2 c. melted butter1/3 c. unsweetened cocoa powder1/3 c. evaporated milk1 lb. powdered sugar
Preheat oven to 350. Lightly grease (and flour, if desired) a 9×13″ pan. Combine the flour, sugar, cocoa powder, baking powder, and salt in a large bowl or the bowl of your stand mixer. Add the melted butter, whisked eggs, and vanilla. Beat on medium speed for about 3 minutes, scraping the bowl occasionally. Add in the chocolate chips and spread the batter in the prepared pan. Bake for 40-50 minutes (or a little less if using a metal pan) or until a pick inserted into the center of the brownies comes out clean.
When the brownies are done, remove from the oven and spread the marshmallows on top. Return the pan to the oven for 2-3 minutes or until the marshmallows are puffed and starting to turn golden brown on top. Remove from oven and cool completely.
While the brownies are cooling, beat together the frosting ingredients on high speed until light and fluffy. Spread over the cooled brownies and cut into squares. Makes about 24 brownies.