Instructions

• Preheat the oven to 350°F. Line one or more baking sheets with parchment paper.
• In a medium bowl, whisk together 1 cup all-purpose flour, ½ cup unsweetened cocoa powder, ¼ teaspoon baking powder, and ¼ teaspoon salt. Set aside.
• In a large bowl, use an electric mixer to beat 6 tablespoons (¾ stick) unsalted butter (room temperature) and ½ cup granulated sugar until light and fluffy, about 2–3 minutes.
• Beat in 1 large egg and ½ teaspoon pure vanilla extract until incorporated.
• Gradually add the flour mixture to the butter mixture and mix just until combined; do not overmix.
• Using a teaspoon, scoop portions of dough and roll into small balls. Place the balls about 2 inches apart on the prepared parchment-lined baking sheets.
• Dip the bottom of a glass in water and flatten each ball into a 1½-inch round about ¼ inch thick.
• Bake the cookies for 8–10 minutes, rotating the baking sheet halfway through baking. The cookies should be slightly firm to the touch.
• Remove the baking sheets from the oven and let the cookies cool completely on the parchment-lined sheets set on wire racks. Keep the parchment on the baking sheets.
• Put 12 ounces chopped bittersweet chocolate, ¼ teaspoon peppermint extract, and 1⁄6 teaspoon salt in a microwave-safe bowl. Microwave in 30-second intervals, stirring after each interval, until the chocolate is smooth. (Alternatively, melt the chocolate in a heatproof bowl set over a pan of simmering water, stirring until smooth.)
• Working with cooled cookies, set a cookie across the tines of a fork and dip the top into the melted chocolate. Tap the underside of the fork on the side of the bowl to remove excess chocolate and create a smooth top.
• Gently transfer each dipped cookie back onto the parchment-lined baking sheet. Decorate with sprinkles or nonpareils, if desired.
• Refrigerate the baking sheet until the chocolate is firm, about 30 minutes. Keep the cookies chilled until ready to serve.