Melt 16 ounces (about 2 1/4 cups) of the chocolate and butter together in a large bowl over a saucepan of simmering water, or in the microwave on 50% powder, checking and stirring every 30 seconds. The mixture may be thick, and that's fine. Set aside.

In the bowl of a stand mixer fitted with the whisk attachment, beat together the eggs and sugar until thick and pale. Beat in the vanilla and salt.

Beat in the melted chocolate (even thought the chocolate mixture is thick, it will blend into the eggs with the whisk attachment). Once the chocolate is completely blended, beat in the flour, baking powder, and salt.

Fold in the remaining chocolate chips (about 1 1/4 cups). Transfer the dough to a large bowl, cover with plastic wrap and refrigerate or freeze until firm. Refrigerating may take 2 hours, and the freezer should take about 45 minutes to 1 hour. You can also prepare this dough one day in advance!

Preheat the oven to 350 degrees. Line two or three large baking sheets with parchment paper. Working with about 1 heaping tablespoon at a time, roll the dough into balls and place the balls on the prepared pan, about 2 inches apart (you can also use a cookie scoop). If the dough sticks to your hands, moisten your hands with water.

Bake for 8 to 10 minutes, until the cookies are cracked on top and slightly dry around the edges (they may seem underbaked in the middle, and that's what we want!).

Cool the cookies on the baking sheets, on wire racks, for 10 minutes before transferring them to the racks to cool completely. If desired, for firmer cookies, pop them in the refrigerator until firm (just like you would with brownies).

Store leftover cookies in an airtight container in the refrigerator.