In a large mixing bowl or stand mixer, whisk together the sifted dark cocoa powder, granulated sugar, and melted butter until a glossy, paste-like mixture forms.

Beat in eggs one at a time, whisking vigorously for 1 full minute after each addition until thick and ribbon-like. Stir in vanilla extract and espresso powder.

In a separate bowl, whisk together all-purpose flour, baking powder, and fine sea salt. Gradually fold the dry flour mixture into the chocolate batter using a rubber spatula just until no flour streaks remain. Gently fold in chocolate chips. (The dough will be soft and sticky like brownie batter).

Cover the bowl tightly with plastic wrap and chill in the refrigerator for at least 2 hours (or overnight) until completely firm and scoopable.

Preheat your oven to 350°F (175°C) and line two large baking sheets with parchment paper. Place granulated sugar and powdered sugar into two separate shallow bowls.

Using a 1.5-tablespoon cookie scoop, portion dough and quickly roll between your palms into smooth 1-inch balls.

Roll each dough ball first in granulated sugar (to seal moisture), then generously toss and coat in confectioners powdered sugar so no chocolate is visible through the thick white powder.

Place sugar-coated balls on the prepared baking sheets spaced 2 inches apart.

Bake for 9 to 11 minutes until the cookies have puffed and crinkled dramatically across the top with set edges, but remain soft and fudgy in the center. Do not overbake!

Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire cooling rack. Enjoy warm with a glass of cold milk!