01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a heatproof bowl set over a pot of simmering water, melt chopped dark chocolate and butter together, stirring until smooth. Remove from heat and let cool slightly.
03 - In a medium bowl, whisk together flour, cocoa powder, baking powder, and sea salt until well blended.
04 - In a large bowl, whisk together granulated sugar, brown sugar, eggs, and vanilla extract until pale and thick, about 2-3 minutes.
05 - Pour melted chocolate mixture into egg mixture and whisk until fully combined and smooth.
06 - Fold dry ingredients into batter using a spatula until just incorporated. Do not overmix to maintain fudgy texture.
07 - Gently fold in chocolate chips until evenly distributed throughout dough.
08 - Using a medium cookie scoop or two spoons, drop heaping tablespoons of dough onto prepared baking sheets, spacing 2 inches apart.
09 - Sprinkle with flaky sea salt if desired for enhanced flavor contrast.
10 - Bake for 10-12 minutes until tops are shiny and cracked but centers remain soft and slightly underdone.
11 - Let cookies cool on baking sheets for 10 minutes, then transfer to wire rack to cool completely.