It's easier than you think to make these popular minty cookies at home.
In a medium bowl, whisk together flour, cornstarch, cocoa powder, and salt until combined. In a separate large bowl, cream together butter and sugar. With an electric mixer on low, add milk and both extracts. Mixture should look curdled. Gradually, add flour mixture until fully incorporated. Shape dough into 2 logs, 2 inches in diameter, and wrap in plastic to freeze for 1-2 hours.
Preheat oven to 375 degrees.
Slice dough into ¼-inch thick rounds and place on a parchment-lined baking sheet. Bake 12 minutes, until cookies are firm at the edges. Cool cookies completely on a wire rack before dipping in chocolate coating.
In a microwave-safe bowl, combine chocolate and butter. Melt in the microwave, stirring every 30 seconds, until chocolate is smooth. Dip each cookie in melted chocolate, turn with a fork to coat, then transfer to parchment paper to set for 30 minutes, or until chocolate is firm. Reheat chocolate as needed to keep smooth for dipping.