If using Oreos, separate and scrape off white cream. Line a baking sheet with wax paper, or other nonstick paper.
Add chocolate chips to a microwave safe bowl. Heat chocolate in 30-second intervals, until completely melted. Stir until smooth. You can also melt with a double boiler. Once melted, stir in peppermint extract. (If chocolate is too thick for dipping, you can stir in a little melted butter or canola oil.)
Place one cookie at a time on top of a fork and dip into the melted chocolate. Flip cookie a few times to coat, then scoop up with fork and tap off excess chocolate.
Place on prepared baking sheet and repeat with each cookie. Refrigerate cookies for 15 minutes to let chocolate set.