Slowly add in the remaining powdered sugar, scraping the sides of the bowl often. Add food coloring if desired. Beat for 2-4 minutes, or till smooth and fluffy.
Scrape all of the mixture into a mound, cover tightly with plastic wrap. Chill for at least an hour.
When the mixture is firm enough to handle, divide it into 5 or 6 pieces. To form mints, sprinkle your counter liberally with powdered sugar. Roll each piece out into a rope about ½" thick.
Use a dough scraper to cut each rope into small pillow-shaped pieces approximately ½" long. Place each mint on a cookie sheet lined with waxed paper. Let mints sit at room temperature for at least 12 hours to dry out.