Preheat the oven to 350°F.
Line two baking sheets with parchment paper; set aside.
Sift flour, cocoa, and baking powder into a medium bowl. Whisk in the salt; set aside.
In a glass bowl over a saucepan of simmering (not boiling) water add chopped chocolate (the bottom of the bowl should not touch the water). Stir occasionally until the chocolate melts and is smooth.
Remove the bowl from the water and allow to cool for 5 to 10 minutes.
In the bowl of a stand mixer, using the paddle attachment, cream butter and sugar together at medium speed until well combined.
Add eggs, one at a time, mixing on medium speed until eggs are incorporated.
Increase mixer speed to high and beat for about 3 minutes, until the mixture is light and creamy, occaisionally scraping the bowl down.
Add melted chocolate and vanilla extract to egg mixture and mix just until combined.
Remove bowl from the mixer and gently fold in dry ingredients with a rubber spatula. Fold in chocolate chips.
As soon as the batter is finished, start scooping the cookies on to the prepared baking sheets. At first the batter will be very soft, but it will harden quickly to a truffle-like texture making it more difficult to scoop.
Use a 3 Tablespoon scoop (see note in post) or a scant 1/4 cup of dough for each cookies.
Space the cookies about 2-inches apart and flatten each cookie lightly with your hand (dampened if you like, as the dough will be sticky).
If you are baking more than one batch, leave the portioned dough at room temperature as refrigerated dough won't spread as it should.
Bake cookies for 14 minutes, rotating the pan after the first 7 minutes. The tops should be crackly across the top, and you can bake them for up to 16 minutes. But don't overcook or you'll lose the lovely soft center.
Remove cookies from the oven and slide, still on the parchment paper, to a wire rack to cool.