Preheat oven to 350° and line two baking sheets with parchment paper or silicone baking mats, and very lightly grease with cooking spray.
In a large bowl, combine powdered sugar, cocoa powder, and salt. Stir in egg whites (they do not need to be beaten or mixed ahead of time) and vanilla then add chocolate chips. Mix well, but do not over mix.
Scoop tablespoon-size mounds onto prepared baking sheets, leave at least two inches between cookies as they will spread. Bake until set, approximately 10 to 12 minutes. Let cool on baking sheet for about 5 minutes then carefully transfer cookies to a cooling rack with a spatula to cool completely.
For shinier cookies, rest dough at room temperature for 20 minutes before baking.
Cookies are fragile when still warm, and a thin spatula works best. To make lifting cookies with a spatula easier, and to prevent cookies from sticking to spatula, lightly spray spatula with non-stick cookie spray prior to using it to lift cookies off baking sheet.
Calories: 122kcal | Carbohydrates: 20g | Protein: 2g | Fat: 5g | Saturated Fat: 3g | Cholesterol: 1mg | Sodium: 34mg | Potassium: 113mg | Fiber: 2g | Sugar: 16g | Vitamin A: 6IU | Calcium: 10mg | Iron: 1mg