Preheat oven to 350 degrees Fahrenheit. Oven racks should be on upper and lower third of the oven. Line 2 baking sheets with parchment paper.
Mix cocoa powder, powdered sugar, and salt in a large bowl. Add in egg whites and egg.
Gently mix in chocolate and cacao nibs.
Drop dough by tablespoons, 2 inches apart on baking sheets.
Bake 14 to 16 minutes. Rotate baking sheet halfway through time. Cookies should be puffed up, the tops cracked and the edges set.
Place pans on wire racks and allow to cool.