Makes 20 cookies
For the cookies:
4 ounces butter, softened
1/2 cup granulated sugar
1/4 cup cocoa powder
1 cup all-purpose flour
For the filling and the coating:
1 1/2 cups powdered sugar
1/2 teaspoon peppermint extract
4 ounces milk chocolate
2 ounces dark chocolate
1 tablespoon coconut oil, or vegetable oil
1 Cream together the butter and sugar until light and fluffy. Scrape down the bowl, add the egg and continue beating until the egg is incorporated and the mixture lightens in color.
2 Add the cocoa powder to the egg mixture and beat until there are no lumps. Finally, fold through the flour until it is all incorporated. The dough will be very soft.
3 Turn it out onto a piece of baking paper, roll it into a log about 1 1/2 inches thick, and wrap the dough. Place the log into the freezer to chill for at least 30 minutes. Preheat the oven to 350° F (180° C) and line two baking sheets with baking paper.
4 Preheat the oven to 350° F (180° C) and line two baking sheets with baking paper. When the dough is finished chilling, take it out of the freezer and slice into pieces just under half an inch thick. You should get about 20 rounds.
5 Place the cookies onto the baking sheets, and bake for 10 minutes. Remove from the oven and leave to cool completely on the baking sheets.
6 To make the mint filling, simply stir together the powdered sugar, the peppermint extract, and 1 tablespoon water. The mixture should be very thick, like the texture of playdough. Take a scant teaspoon of the mint filling and put it atop each cookie, using your fingers to pat and smooth it down to cover the top but stopping shy of the edge of the cookie.
7 To coat the cookies, melt the chocolates and the coconut oil together in the microwave in short bursts, stirring well between each until you have a smooth mixture.
8 Once the chocolate mixture has cooled slightly, dip each cookie in the chocolate, coating it completely. Set them on a rack over a piece of foil or parchment paper to drip and set. Once they're set, these should be stored in the fridge, where they'll keep well for at least a week. They also freeze beautifully for up to a month in an airtight container, and they even taste great straight out of the freezer.