Melt the chocolate and butter: Add the chopped chocolate (or chips) and butter to a heat-safe bowl and melt until smooth and glossy. Stir well to ensure no butter streaks remain. Let it cool slightly—you want it warm, not hot.

Whisk eggs and sugars until frothy: In a large bowl, whisk the eggs with the granulated sugar and packed brown sugar for 3–5 minutes until the mixture is lighter in color, thickened, and frothy on top.

Combine the wet ingredients: Stir in the melted chocolate mixture and vanilla until the batter is evenly dark and shiny.

Sift and fold in the dries: In a separate bowl, sift together the flour, cocoa powder, baking powder, and salt. Fold this into the chocolate mixture just until you stop seeing dry streaks—do not overmix.

Optional chill for thicker cookies: If you prefer a taller cookie, chill the dough for 20–30 minutes.

Preheat the oven to 350°F (175°C) and line baking sheets with parchment paper. Scoop portions of dough onto the sheets, leaving space between them.

Bake for 10–12 minutes, until the edges look set and the tops are crackly and shiny, with soft centers.

Let the cookies cool on the baking sheet for a few minutes, then transfer to a wire rack to cool completely.