How to Make It
Preheat oven to 350°F. Microwave chocolate and butter on HIGH in a medium-size microwavable bowl until just melted and smooth, about 1 minute, stirring after 30 seconds. Add eggs, flour, cocoa, baking powder, and 1½ cups of the powdered sugar; stir until combined.
Using a 1½-inch cookie scoop, drop spoonfuls of dough into remaining 1 cup powdered sugar; roll to evenly coat. Place cookies 1½ inches apart on a parchment-lined baking sheet. Bake until cookies are no longer shiny, 8 to 10 minutes. Cool cookies on baking sheet 5 minutes. Transfer cookies to a wire rack to cool completely, about 30 minutes.