Chop walnuts, then lay on a baking sheet and bake in a (preheated) 350*F oven for 6 minutes. Allow to cool.
Prepare two baking sheets by lining with parchment paper or a Silpat type liner, and set aside.
In the bowl of an electric mixer (or use an electric hand mixer) beat egg whites until they are well combined, white and foamy, but are not stiff (about 2 minutes on medium-low speed). Add vanilla.
In a medium bowl combine the powdered sugar, cocoa, salt, walnuts and chocolate chips. Stir to combine.
Add the bowl of dry ingredients to the bowl of beaten egg whites and stir with a spatula just until well combined. The batter will look similar to a brownie batter.
Use a 2 tablespoon sized cookie scoop to scoop mounds of batter onto the prepared baking sheet. Space the batter several inches apart (6 cookies per baking sheet).
Bake cookies in a (preheated) 350* oven for 11-13 minutes, until the cookies are puffed, shiny and cracked. Remove baking sheet from oven and allow cookies to cool on the baking sheet at least 3-5 minutes. When the cookies have cooled, pull up one end of the parchment paper or Silpat and gently peel the liner off of each cookie. Move the cookies to a cooling rack.