Cream butter and sugars in a large mixing bowl till fluffy. Beat in eggs and vanilla.
In a small bowl, whisk together the flour, cocoa, baking soda, baking powder, and salt. Stir into the wet ingredients just till combined.
Roll dough into tablespoon sized balls. Place onto lightly greased or silpat lined cookie sheets.
Bake at 350 for 9-10 minutes.
Move to cooling racks and cool completely.
For frosting: Beat soft butter, powdered sugar, milk, peppermint extract, and salt, together till smooth and creamy. Add food coloring and enough milk to get a spreadable consistency.
Spread each cookie with mint frosting.
Place chocolate chips on a ziplock bag and melt at 50% power in the microwave.
Drizzle melted chocolate on top of the cookies.