Put the chocolate and the coconut oil in a small glass bowl and microwave for 1 minute. Stir, then put back in the microwave for another minute. Stir to melt all the chocolate. If there are still lumps, microwave very briefly again. Stir in the peppermint extract. You may add more if you want a stronger mint flavor, but I suggest tasting it first.
Using a fork or chocolate dipping tool, dip each cookie into the chocolate and gently flip over to completely coat. Gently tap off the excess chocolate by rapping the fork against the side of the bowl, and lay the cookies on a parchment covered baking sheet. When you have finished all the cookies, put the pan in the refrigerator to harden the cookies.
I like to store the cookies in the refrigerator and enjoy them cold.