Sift together powdered sugar, cocoa, and salt in a large bowl.
Whisk egg whites until frothy (hand mixer works great). Stir egg whites and vanilla into powdered sugar mixture. The batter will be very thick. Stir in chopped chocolate and pecans until well combined.
Drop cookies 3-inches apart using a 1½-inch cookie scoop (about 2 tablespoons) on a parchment-lined baking sheet lightly greased (otherwise they will stick) with cooking spray.
Bake until tops are shiny and cracked, about 8 - 10 minutes. Cool on baking sheet for 5 minutes before transferring cookies to a wire rack to cool completely.
Recipe by My Lilikoi Kitchen at https://www.mylilikoikitchen.com/2020/10/18/fudgy-flourless-chocolate-pecan-cookies/