Whip whites and sugar together in a large mixing bowl with an electric mixer. Sift together cocoa and powdered sugar. Fold the dry ingredients into the meringue when it has reached full volume. Then fold in the cocoa nibs. Spread the chocolate meringue onto a parchment paper lined sheet pan, sprayed with nonstick spray, about 1/4-inch thick.
Bake for about 1 hour or until the meringue is hard and completely dried out.