Set the oven to 350F
Cream butter until light and fluffy, then add the powdered sugar and mix until combined. Stir in the salt, vanilla and cocoa powder. Mix until the cocoa powder is integrated and the batter resembles a thick frosting. Add the flour and mix just until the flour is combined, making sure to not over mix.
Form dough into a ball. Knead a few times to bring together, then flatten into a disk between half an inch and one inch thick, cover in plastic wrap then place in freezer for 15 minutes.
Remove dough from the freezer and roll it out really thin on a floured surface, about 1/8-inch. Cut cookies using 1 1/2-inch cutter (I used a small cordial glass that measured almost 2″ and it was the perfect size).
Place cookies on a baking sheet and bake for 10 minutes. Remove the cookies from the oven and allow them to cool completely on a wire rack. While the cookies bake, make the peppermint coating. Chop the baking chocolate into very small, thin pieces. Place in a glass measuring cup or similar container along with the oil and microwave in short 15-20 second bursts. Stir in the peppermint extract. Feel free to add more peppermint as you see fit. (Don’t add any more, the amount is perfect)
Gently drop the cookies, one at a time, into the coating. Turn to coat entirely, then lift the cookie out of the chocolate with the fork and bang the fork on the side of the pan until the extra coating drips off. Place on a parchment or plastic wrap-lined baking sheet, and repeat for the rest of the cookies. Place the cookies in the refrigerator or freezer to set.
