1. Sift together the flour, cocoa, baking powder, and salt in a medium bowl; set aside.
2. Melt the chocolate in a medium heatproof bowl set over a pan of almost-simmering water, stirring once or twice, until smooth; remove from the heat. (Alternatively, you could melt the chocolate in the microwave.) In a small bowl, beat the eggs and vanilla lightly with a fork, sprinkle the coffee powder over to dissolve, and set aside.
3. Either by hand or with an electric mixer, beat the butter at medium speed until smooth and creamy, about 5 seconds. Beat in the sugars until combined, about 45 seconds; the mixture will look granular. Reduce the speed to low and gradually beat in the egg mixture until incorporated, about 45 seconds. Add the chocolate in a steady stream and beat until combined, about 40 seconds. Scrape the bottom and sides of the bowl wit a rubber spatula. With the mixer at low speed, add the dry ingredients and mix until just combined. Do not overbeat. Fold in the chocolate chips. Cover with plastic wrap and let stand at room temperature until the consistency is scoopable and fudge-like, about 30 minutes.
4. Meanwhile, adjust the oven racks to the upper- and lower-middle positions and heat the oven to 350 degrees. Line 2 baking sheets with parchment paper. Scoop the dough onto the prepared baking sheets with a 1¾-inch ice cream scoop, spacing the mounds of dough about 1½ inches apart.
5. Bake until the edges of the cookies have just begun to set but the centers are still very soft, about 10 minutes, rotating the baking sheets front to back and top to bottom halfway through the baking time. Cool the cookies on the sheets about 10 minutes, slide the parchment with cookies onto wire racks, and cool to room temperature. Cover one cooled baking sheet with a new piece of parchment paper. Scoop the remaining dough onto the parchment-lined sheet, bake, and cool as directed. Remove cooled cookies from the parchment with a wide metal spatula.