Preheat your oven to 350°F (175°C) and line a large 15×21 inch baking sheet with parchment paper.

In a saucepan or microwave-safe bowl, melt the butter and chopped dark chocolate together until smooth. Set aside to cool slightly.

In a medium bowl, whisk together the all-purpose flour, cocoa powder, salt, and baking powder until well combined.

In a large mixing bowl, combine the granulated sugar, light brown sugar, room temperature eggs, and vanilla. Beat on high speed for 7 minutes.

Add the slightly cooled chocolate-butter mixture to the egg mixture and mix until just combined.

Gently fold in the dry ingredients until no flour streaks remain, resulting in a soft batter.

Using a 1 tablespoon cookie scoop, portion the dough onto the prepared baking sheet, spacing them about 1½ inches apart.

Bake for 11-12 minutes until the tops have cracked but the centers are slightly underdone.

Optional: Use a circular cookie cutter to shape the cookies after removing from the oven for a perfect round shape.

Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack and sprinkle with flaky sea salt if desired.