Step 1

Preheat oven to 350 degrees F. Line 2 large baking sheets with parchment paper. Coat the paper with cooking spray.

Step 2

Combine confectioners' sugar, cocoa powder and salt in a medium bowl. Beat egg whites in a large mixing bowl with an electric mixer until soft peaks form. Add vanilla. Fold in the cocoa powder mixture with a rubber spatula until combined. Fold in chocolate chips (or chunks).

Step 3

Drop the batter by tablespoonfuls onto the prepared baking sheets, leaving about 2 inches between each cookie. Bake, one sheet at a time, until the cookies are just beginning to crack on top, 12 to 14 minutes. Let cool slightly on the pan before transferring to a wire rack to cool completely.