1. Sift together flour, cocoa, baking powder and salt into medium bowl, set aside.
2. Melt chocolate in a medium heat-proof bowl set over pan of almost simmer water, stirring once or twice, until smooth. Remove from heat. Or melt in microwave: heat at 50% power for 2 minutes, stir, then heat another minute at 50% power. If it is not completely melted, continue heating, for 30 second increments at 50%, stirring after each time, until smooth. Be very careful not to burn it! Beat eggs and vanilla lightly in a small bowl with a fork, sprinkle coffee powder over, and stir to dissolve.
3. In the bowl of a standing mixer fitted with the paddle attachment, beat butter at medium speed until smooth and creamy, about 5 seconds. Beat in sugars to combine, about 45 seconds, mixture will look granular. Reduce speed to low and gradually beat in egg mixture until incorporated, about 45 seconds. Add chocolate in steady stream and beat until combined, about 40 seconds. Scrape bottom and sides of bowl with a rubber spatula. With mixer at low speed, add dry ingredients and mix until just combined. Then mix in chocolate chips -- do not over beat! Cover bowl with plastic wrap and let stand at room temperature until consistency is scoop-able and fudge-like, about 30 minutes.
4. Meanwhile, adjust oven racks to upper-middle and lower-middle positions, and preheat to 350 degrees F. Line two baking sheets with parchment paper. Leaving about 1 1/2 inches between balls, scoop dough onto cookie sheets using an ice-cream scoop. The balls should be about the size of golf balls.
5. Bake, reversing position of baking sheets halfway through baking (from top to bottom and front to back) until edges of cookies have just begun to set, but centers are still very soft, about 10 minutes. The cookies will look like they are not done, but don't bake them any longer than this -- they will firm up as they cool.
6. Cool cookies on baking sheets for about 10 minutes. If using parchment, then carefully slide the parchment with cookies onto wire racks, and let cool to room temperature.