1cup(142g)all-purpose flour, plus more for surface
½cup(43g)unsweetened Dutch-process cocoa powder or natural cocoa powder (see note)
5tablespoonssalted butter, softened
¾teaspoonpure peppermint extract
Peppermint candies, crushed (optional)
2poundswhite or dark chocolate, coarsely chopped (or a combination if you want to dip some in white chocolate and the rest in dark)
Preheat the oven to 325 degrees.
In a small bowl, whisk together the flour, cocoa powder, baking soda, baking powder, and salt.
In a medium bowl (or the bowl of an electric stand mixer), beat the butter and sugar with a mixer on medium-high speed for 1 minute. Reduce the speed to medium-low and add the egg and egg yolk. Mix well. Beat in the peppermint extract.
Slowly add the flour mixture, and beat until just incorporated. Shape the dough into 2 disks, wrap each in plastic, and refrigerate until firm, at least 1 hour (or up to 2 days).
Roll out 1 disk of dough on a lightly floured surface to 1/8-inch thickness, more or less. Using a 2-inch round cutter, cut out circles and place 1-inch apart on parchment-lined baking sheets. Roll and cut the scraps once or twice (the cookies will be a bit more dry with each rerolling). Freeze the tray of cookies until firm, about 15 minutes. Repeat with the remaining disk of dough and freeze also.
Bake the frozen cookie rounds until they are dry to the touch, about 12-14 minutes. It's really important to bake them all the way through so they are crisp and not soft.
Transfer the baked cookies to a wire rack to cool completely. The undipped cookies will keep well , covered, for up to 3 days.
Melt the chocolate in a heatproof bowl in the microwave or in a double boiler on the stove. I like to melt it in the microwave at 1-minute intervals at 50% power, stirring in between. Melt the white and dark chocolate separately, if using both.
Dunk the cooled cookies into the melted chocolate, one at a time. Using a fork, press lightly on the cookie until completely submerged in the chocolate. Pick up the cookie with the fork, let the excess chocolate drip off, and gently scrape bottom against edge of bowl. Using the flat edge of a knife or another fork, gently push the cookies onto parchment or wax paper. Sprinkle with crushed candy if using. Let the cookies sit until the chocolate has hardened, an hour or so (you can refrigerate to speed up this process).
The dipped cookies will keep covered in the refrigerator for up to a week or in the freezer for up to a month.
Cocoa Powder: I have used both Dutch-process and natural cocoa powder when I've made these. The Dutch-process will yield a darker, richer cookie center but the natural cocoa powder is also delicious and will work just fine.Chocolate: here's a quick video tip on tempering/melting chocolate and another on dipping things in chocolate like a pro.Brand: FYI: My preferred brand of chocolate is Ghirardelli.