1Preheat oven to 375°F and line two baking sheets with parchment paper.
2Whisk the egg whites and powdered sugar together until smooth, glossy, and fully combined, ensuring no graininess remains.
3Fold in the cocoa powder, salt, and vanilla until just combined.
4Fold in the chocolate chips until evenly distributed.
5Drop about 2 tablespoons of batter per cookie onto the prepared baking sheets, ensuring they are spaced at least 3 inches apart.
6Bake for 2 minutes at 375°F, then immediately reduce the oven to 350°F and continue baking for 8 to 9 minutes, until the tops are shiny and crackly but the centers still look soft.
7Cool on the baking sheet for at least 10 minutes before transferring to a wire rack.