Preheat the oven to 350 F. In a large bowl, combine butter with 1/2 cup powdered sugar until fluffy. Add in peppermint extract, and mix until smooth.
Add in flour, and mix until a thick dough forms. Add in green food coloring, mix until fully green. Fold in chocolate chips.
Roll the cookie dough into balls, and place at least 2-inches apart onto ungreased baking sheets. Bake for 10-12 minutes.
Place the remaining 1/2 cup powdered sugar into a shallow dish. Roll the baked cookies into the sugar, and let cool on cooling racks.
