"Leave out the mint and you have an excellent homemade version of the best-known chocolate sandwich cookie in America. But add a little mint to the cookie and the filling, and you get heaven in a cookie: dark chocolate and fragrant mint with a creamy filling. These are good at room temperature, but as anyone who has ever frozen a Girl Scout Thin Mint can tell you, even better if you store them in the freezer. Use real peppermint oil, not peppermint extract, for the best flavor...."