01 -
Sift together the powdered sugar, salt, and cocoa in a large bowl.
02 -
Add egg whites and vanilla extract to the dry mixture and stir carefully until a thick batter forms. If the mixture is too crumbly, add the third egg white.
03 -
Stir in the chocolate chips and nuts, if using, and let the batter sit for 30 minutes before scooping.
04 -
Preheat the oven to 350°F. Line two baking sheets with parchment paper and spray with nonstick cooking spray or grease. For silicone baking mats, spray them as well.
05 -
Scoop 1-2 tablespoon-sized balls of dough onto the prepared baking sheets, leaving a few inches between them as the cookies will spread.
06 -
Bake for 13-15 minutes until most of the cookies are no longer glossy, leaving only small glossy spots in the centers. Let the cookies cool completely before removing using a spatula.
07 -
Store the cooled cookies in an airtight container for up to 3 days or freeze for up to a month.