Adjust rack to middle and heat oven to 325˚. Line 2 baking sheets with parchment. Combine chocolate and butter in bowl and microwave at 50 percent power, stirring occasionally, until melted, 2 to 3 minutes. Cool.

Whisk together brown sugar, eggs, coffee powder, and vanilla together in large bowl. In another bowl, whisk together flour, cocoa, baking powder, baking soda, and salt.

Whisk cooled chocolate mixture into egg mixture until combined. Fold in flour mixture until no dry streaks remain. Refrigerate for 10 minutes.

Place granulated sugar and confectioners’ sugar in separate shallow dishes. Working with 2 tablespoons of dough at a time, roll into balls. Drop dough balls directly into granulated sugar and roll to coat. Transfer dough balls to confectioners’ sugar and roll to coat evenly. Space evenly on prepared sheets.

Bake cookies, 1 sheet at a time, until puffed and cracked and edges have begun to set but centers are still soft (cookies will look raw between cracks and seem underdone), about 12 minutes, rotating sheet halfway through baking. Let cool completely on sheet before serving.