Beat the 10 egg whites, cream of tartar and salt in a mixing bowl with an electric mixer on low speed until frothy. Gradually increase the mixer speed to medium-high and beat until soft peaks form. While still beating, slowly add the remaining 3/4 cup sugar and beat until semi-stiff peaks form. Fold the egg yolk mixture into the beaten egg whites with a rubber spatula, then fold in the grated chocolate chips. Sprinkle about 1/3 cup of the reserved flour mixture over the top and gently fold in; repeat with the remaining flour, adding 1/3 cup at a time.