Preheat the oven to 350F. Line 2 large baking trays with parchment paper or a silicone mat and set aside.

In a small bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.

In a microwave-safe bowl, add the chocolate and butter. Heat in 30 second intervals, stirring after each one, until melted and smooth. Set aside.

Using either a hand mixer or a stand mixer fitted with the whisk attachment, beat together the eggs and sugar until pale, fluffy, and tripled in volume - about 5 minutes.

Add the chocolate mixture and vanilla, and whisk until combined.

Add the dry ingredients and fold in until smooth and combined. The batter will be very runny.

Refrigerate for 15 minutes until thickened slightly and resembles more like a thick brownie batter when mixed.

Using a medium cookie scoop, divide all of the batter out between the prepared baking trays.

NOTE: Scooping out all of the dough at once onto baking trays is key to shiny, crinkly tops on all cookies.

Bake for 10 - 12 minutes (one tray at a time) or until the tops are shiny and cracked, and the cookies have domed slightly.

Allow to cool on the baking trays for at least 15 - 20 minutes (they will be very soft) before transferring them to a wire rack to cool completely.