1. Melt the chopped dark chocolate and butter in a heatproof bowl over a double boiler or microwave in 30-second bursts, stirring in between. Let cool slightly.

2. In a mixing bowl, whisk together eggs, granulated sugar, and brown sugar until light and fluffy (about 3–5 minutes).

3. Stir the melted chocolate mixture and vanilla extract into the egg mixture until fully combined.

4. Sift together the flour, cocoa powder, baking powder, and salt. Gently fold into the wet mixture. Do not overmix.

5. Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.

6. Use a cookie scoop to portion the batter onto prepared sheets, leaving space to spread.

7. Sprinkle tops with flaky sea salt if desired.

8. Bake for 10–12 minutes, until tops are glossy and cracked but centers are slightly soft.

9. Let cool on the tray for 5 minutes, then transfer to a wire rack.