1-First, in a medium bowl, whisk together the 2 cups (260 g) all-purpose flour, ½ cup (42 g) unsweetened Dutch-processed cocoa powder, and ½ teaspoon salt; set aside. Next, beat the 1 cup (226 g) unsalted butter, softened, and ⅔ cup (113 g) granulated sugar on medium speed until smooth and creamy, about 3 minutes. Add the 1 large egg white, 1 teaspoon vanilla extract, and ½ teaspoon peppermint extract; mix well (the dough may appear curdled, which is normal).

2-Gradually add the flour mixture in three additions, mixing just until incorporated after each, and scrape down the bowl sides as needed. Divide the dough in half and place each half between two pieces of parchment paper. Roll to ¼ inch thickness, then transfer with parchment to a baking sheet. Stack the dough slabs with parchment between them if needed and refrigerate for at least 3 hours or freeze for 1 hour.

3-Preheat and Bake: Preheat the oven to 350°F and line baking sheets with parchment paper. Remove the top parchment layer and cut 2-inch circles from the dough using a cookie cutter. Place the cookies 1½ inches apart on the baking sheets, re-rolling scraps as necessary. Bake for 15-18 minutes until the cookies feel firm, then cool for 5 minutes on the baking sheet before transferring to a wire rack to cool completely.

4-For the coating, melt the 12 ounces (339 g) dark or semisweet chocolate, coarsely chopped, ½ teaspoon vegetable oil, and ¼ teaspoon peppermint extract in a heatproof bowl set over simmering water, stirring until smooth. Dip each cooled cookie in the melted chocolate, turning to coat fully and tapping off excess. Place on a parchment-lined sheet and refrigerate for 10 minutes until set. Serve the cookies cold for the best texture, and remember, the active prep time is about 35 minutes, with baking taking 15-18 minutes per batch.