Preheat the oven to 350°F.

Add butter along with the dark chocolate to a heat-proof bowl, place the bowl over a pot of simmering water. Stir to melt the butter and chocolate. Set aside to cool down.

In the bowl of a stand mixer, add eggs and sugar. Stir to combine, then increase the mixer to medium speed and beat for 4-5 minutes until creamy.

In the meantime, sift flour, cocoa powder, and baking powder into a small mixing bowl. Add the salt and mix with a whisk to distribute evenly. Set aside.

Once the egg mixture is done mixing, add vanilla and the cooled melted chocolate/butter mixture; beat for about a minute to combine. Reduce the mixer speed to stir and slowly add the dry ingredients set aside earlier; mix until just combined.

The final batter is thick but still a bit runny, more like a brownie batter; not doughy like a typical cookie dough. Use a spatula to scrape down the whisk attachment, the side, and the bottom of the bowl. Give it a final stir to make sure everything is combined evenly.

Line a baking sheet with parchment paper and use a 1.5 oz cookie scoop to portion the batter. Scoop and level with a spatula, and drop it on the prepared baking sheet at least 2 inches apart.

Bake for 11 minutes, remove from the oven, and let the baking sheet rest on a wire rack for 5 - 10 minutes before removing the cookies to the wire rack to cool completely.

Repeat with the rest of the batter, only baking one tray at a time.