Preheat the oven to 350°F and line two large cookie sheets with parchment paper.
Cut the butter into slices and place those slices and the dark chocolate into a microwave safe bowl. Microwave them for 30 seconds, stir, and then continue microwaving for 20 second intervals, stirring between each until the chocolate is fully melted.
Stir in the cocoa powder until smooth and dissolved. Set this chocolate mixture aside to cool down.
In the bowl of an electric mixer fitted with the paddle attachment, beat the eggs, granulated sugar, and brown sugar together on medium-high speed for 6 minutes until they are very light and fluffy.
Then, beat in the cooled down chocolate mixture and vanilla extract until fully combined.
In a separate bowl, sift together the flour, baking powder, and salt. Then, add this into the remaining ingredients and mix until the flour is combined. Lastly, fold in the chocolate chips. The dough will resemble a very thick brownie batter.
Scoop 1.5 tbsp balls of dough into the prepared cookie sheets, leaving 2 inches of space between each.
Bake for 11-12 minutes, or until cookies are set. Let the cookies rest for 5 minutes on the cookie sheets before transferring them to wire racks to cool completely. Enjoy!