Preheat oven to 350 degrees F. Line 2 baking sheets with parchment paper.
Place granulated sugar in shallow dish; set aside.
Combine flour, cocoa, baking soda, and baking powder in bowl.
In another bowl beat butter, brown sugar and salt together until fluffy.
Add in eggs and vanilla.
Mix in flour mixture and mix well.
Form dough into balls and roll in granulated sugar.
Place on a parchment lined baking sheet and use hand or the bottom of a glass dipped in sugar to flatten cookie.
Bake for 10 minutes. Do not overbake.
Mix together frosting ingredients. Adding enough milk to get a nice spreading consistency.
Sprinkle with chopped up Andes Mints