Yield: about 50 cookies
In a medium bowl, whisk together flour, cocoa powder, salt, baking powder, and baking soda. Set aside.
In the bowl of a stand mixer with a paddle attachment, beat together sugar and coconut oil on medium-high speed. Beat until mixture if fluffy. Reduce speed to low and add milk, egg, and vanilla paste.
With the mixer still on low, slowly add the prepared flour mixture. Mix until just combined. Divide dough into two equal parts. Flatten the two halves and wrap tightly in plastic wrap. Chill in the refrigerator for 30-45 minutes until dough is cold and firm.
Preheat oven to 350 degrees. Line baking sheets with parchment paper and set aside.
Work with one dough at at time. On a lightly floured work surface, roll dough to 1/4”. Using a 1 3/4” round cutter, punch out cookies. Transfer to prepared baking sheet. Space cookies about 1/2” apart from each other. Bake in preheat oven for 15 minutes, rotating sheets halfway through baking. Let cookies cool in the pan for a couple minutes before transferring to a wire rack to cool completely.
Line baking sheet with parchment paper. Place clean wire rack on top. Set aside.
Melt together chocolate and peppermint oil in a medium metal or glass bowl over a small pot filled with an inch of barely simmering water. Stir chocolate until melted. Slowly melt the chocolate, by moving the bowl on and off the heat every 30 seconds or so to prevent overheating
Once chocolate is melted, remove bowl from heat and set over a folded kitchen towel. Do not set bowl on marble or other kitchen surface that will cool down the bowl. Working with one cookie at a time, drop cookie into melted chocolate. Using a fork to scoop cookie from the bottom. Tap fork on the edge of the bowl to let any excess chocolate drip from the cookie. Transfer cookies to prepared wire rack to let chocolate harden. If desired, make swirl marks on top of chocolate. Otherwise leave alone and your cookies will be smooth on top.
*If chocolate is taking longer than 10-15 minutes to harden, place cookies in the fridge. However, if you end up doing this, you will have to store your cookies in the fridge. Otherwise they will melt at room temperature.
ADAPTED FROM THE AMERICA'S TEST KITCHEN D.I.Y. COOKBOOK