I love Thin Mints.  I teach in an elementary school which means that I get asked to buy a lot of 
Girl Scout cookies.  Do I mind this? Most def. not!  I always buy an obscene amount of thin mints and they always mysteriously seem to disappear.  Well since we are out of girl scout cookie season, I decided to try The Little Kitchen That Could's 
Thin Mint recipe.
(This is not a recipe the can be made quickly in one afternoon.  There is a lot of freezing/cooling that has to occur between steps).
Thin Mints
From the Little Kitchen that Could
Ingredientsfor the cookies: 2 1/4 cups all purpose flour
1/4 cup cornstarch
6 tablespoons unsweetened cocoa powder
1/2 teaspoon salt
1 cup white sugar
1/2 cup unsalted butter, room temperature
1/3 cup milk (any kind)
1/2 teaspoon vanilla extract
3/4 teaspoon peppermint extract
for the coating:12 ounces dark or semisweet chocolate
1/2 cup butter, room temperature
parchment paper
Step by StepIn a small bowl, whisk together flour, cornstarch, cocoa powder and  salt.  In a large bowl, cream together butter and sugar until fluffy.   With mixer on low speed, add the milk and the extracts.  The mixture  will resemble curdled milk. Slowly add the flour mixture until well  incorporated and fluffy.
Shape dough into two long logs, about 1 1/2 inches in diameter (4 cm).   Wrap in plastic wrap and freeze for at least 2 hours, until very firm.

Preheat oven to 375 degrees F. Using a sharp knife, slice dough into  round no more than 1/4 inch thick. Slice carefully so they are as close  to the same thickness as possible.  You will have some very soft and  others very hard if they differ too much in thickness.  Make sure they  are no more than 1/4 inch thick or they won't be crispy.  Place on a  parchment lined baking sheet.  Cookies can be very close together  because they will not spread much at all.

Bake for 13 minutes (see recipe notes); until the edges of the cookie  are firm.  Allow cookies to cool completely.  In a microwave safe bowl,  combine chocolate and butter. Microwave on high power for 30 seconds.   Remove and stir; continue microwaving in 30 second increments, stirring  between each, until chocolate and butter are completely melted and  smooth.
Dip each cookie in melted chocolate and rotate to cover whole cookie.   Using a fork, scrape off extra chocolate so there is a thin coating.   Place cookies on parchment paper or wax paper to allow to cool and set;  at least 45 minutes.  Reheat chocolate as necessary to keep is smooth  and easy to dip into.

*I keep these cookies frozen until ready to serve.  They do not taste exactly like Thin Mints, but do have the yummy chocolate/minty combo.