I used peppermint oil for these, because that's what I had, and since it is much stronger than extract i just used a few drops. The cookies themselves were perfectly minty, but once covered in the white chocolate, we felt they could have used just a bit more mint flavor. Next time I would err on making the cookies just slightly too minty so when they are all done, they will be the perfect balance of chocolate and mint. So don't be afraid to use slightly more extract if needed to suit your taste.
Chocolate Peppermint Cookies
(Adapted from Martha Stewart Living, December 2008 via Movable Feasts)
1 cup all purpose flour plus more for surface
1/2 cup unsweetened Dutch-process cocoa powder
1/2 teaspoon baking soda
1/2 teaspoon baking powder
1/2 teaspoon salt
5 tablespoons unsalted butter, room temperature
3/4 cup sugar
1 large egg
1 large egg yolk
3/4 teaspoon pure peppermint extract
8 large candy canes or 30 peppermint candies, crushed
2 pounds white chocolate, coarsely chopped
Preheat oven to 325°. Sift flour, cocoa powder, baking soda, baking powder and salt into a bowl.
Beat butter and sugar with a mixer for 1 minute. Add egg, then yolk, beating well after each addition. Beat in peppermint extract. Slowly add flour mixture and beat just until incorporated. Mold dough into 1 large disk and cut in half. Wrap each in plastic wrap and refrigerate until firm, at least an hour (or up to two days).
Roll out 1 disk on a lightly floured surface to 1/8 inch thickness. Use a 2" cookie cutter to cut out circles and place them on parchment paper. Freeze until firm, at least 15 minutes.
Repeat with remaining disk.
Bake until cookies are dry to the touch, about 12 minutes. Transfer parchment, with cookies, to wire racks and allow to cool. Make sure that your cookies are complete baked you do not want a soft center.
Melt chocolate in a heatproof bowl set over a pot of gently simmering water. Remove from heat and dunk cookies into the melted chocolate. Turn cookies using a fork; let excess drip off and gently scrape the bottom of the cookies against the edge of the bowl. Place on parchment lined baking sheets and sprinkle with the crushed candy.
Refrigerate until set, up to 3 hours. Decorated cookies are best served the same day. (I have successfully kept these cookies for 2 weeks stored in an air tight tin and hidden from my family)
Martha says you will get about sixty 2 inch cookies but I only got about 3 1/2 dozen. Next time I will use a 1 3/4 inch cutter since the baked cookies would then be about 2 inches.