1. Line two baking sheets with parchment paper and spray with nonstick spray.
  2. In a large bowl, whisk together powder sugar, salt, and cocoa powder. Stir in egg whites and vanilla extract until the batter is completely moistened. It will be very thick. Gently stir in the chocolate chips.
  3. Spoon the batter on the sprayed parchment lined sheets, 12 mounds per sheet. Preheat the oven to 350º. Let the cookie sheets rest for 30 minutes before baking. The cookies will almost develop a crust on them. Bake for 10-12 minutes until tops are glossy and lightly cracked.
  4. Let the cookies cool for a few minutes on the baking sheet before gently transferring them to a cooling rack to finish cooling.