Preheat oven to 350F. Line a 9x9 in pan with either foil or parchment paper. In a large , melt together the chocolate and the butter. Whisk in the sugar.
Add the eggs, yolks, and vanilla and whisk until combined. Fold in the dry ingredients.
Spoon about 1/2 the batter into the bottom of the pan. Lay down the Andes Mints, covering the whole layer of batter. Spread the remaining batter on top of the candies. Bake for 35 minutes. Allow to cool completely before frosting
Cream together the butter and mint extract until fluffy. Add the powdered sugar and beat until mixed. Beat in the milk, stir in the chocolate chips
Spread the frosting onto the brownies, cut, and enjoy!