A light and airy cookie stuffed full of semi-sweet chocolate chips.
Heat oven to 350ºF.
Cover cookie sheet with parchment paper or foil.
In large mixer bowl, beat egg whites and cream of tartar on high speed of electric mixer until soft peaks form. Gradually add sugar and vanilla, beating well after each addition until stiff peaks hold their shape, and sugar is dissolved and mixture is glossy.
Sift cocoa over egg white mixture; gently fold in just until combined. Fold in chocolate chips. Drop mixture by heaping teaspoonfuls onto prepared cookie sheet.
Bake 35-40 minutes or just until dry.
Cool slightly; peel paper from cookies. Cool completely on wire rack. Store covered, at room temperature.