Preheat oven to 350°F. Line a large cookie sheet with parchment paper; set aside.
In a large bowl stir together cookie mix, butter, egg, and mint extract until a soft dough forms. Stir in chopped chocolate-mint candies.
Drop dough by rounded teaspoons 2 inches apart onto the prepared cookie sheet. Bake for 8 to 10 minutes or until set.
Place a coating disk on top of each cookie. Cool cookies on cookie sheet for 1 minute. Transfer to a wire rack; cool.
Layer cookies between sheets of waxed paper in an airtight container; cover. Store at room temperature for up to 3 days or freeze up to 3 months.
Look for green candy coating disks or wafers in the cake decorating section of hobby and craft stores, the most common brand being Wilton.