In a microwave-safe bowl, combine the chopped chocolate and butter. Microwave in 20-second intervals, stirring between each, until the mixture is melted and smooth. Set aside to cool slightly.

In a mixing bowl, beat the granulated sugar, light brown sugar, eggs, and vanilla extract with an electric mixer on medium speed until the mixture becomes light and frothy, about 3 to 5 minutes.

Slowly add the cooled chocolate mixture into the egg mixture and blend well until fully incorporated.

Gently fold in the all-purpose flour, unsweetened cocoa powder, baking powder, and salt until just combined. Avoid overmixing to keep the batter fudgy.

Cover the bowl and chill the batter in the refrigerator for 30 minutes. This helps firm up the dough for better cookie shape.

Preheat your oven to 350°F. Line a baking sheet with parchment paper. Use a cookie scoop (about 1.5 tablespoons of dough per cookie) to place balls of dough about 2 inches apart onto the sheet.

Bake for 8 to 12 minutes until the edges are set and the top shows a shiny, crackly look. Do not overbake to keep a fudgy texture.

Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack. Sprinkle with flaky sea salt if desired.