01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a large bowl, cream together butter, granulated sugar, and brown sugar until light and fluffy.
03 - Beat in eggs one at a time, then mix in vanilla and peppermint extracts.
04 - In a separate bowl, whisk together flour, cocoa powder, baking soda, and salt.
05 - Gradually add dry ingredients to wet ingredients, mixing until just combined. Fold in chocolate chips.
06 - Drop tablespoon-sized balls of dough onto prepared baking sheets, spacing 2 inches apart.
07 - Bake for 8-10 minutes until cookies are set but still soft in center. Cool on sheets for 5 minutes, then transfer to wire rack.
08 - Beat butter until creamy. Gradually add powdered sugar, milk, peppermint extract, food coloring, and salt. Beat until smooth and fluffy.
09 - Once cookies are completely cool, spread or pipe green frosting on top of each cookie. Allow frosting to set before serving.