In medium bowl, beat egg whites and cream of tartar with electric mixer on low speed until foamy. Increase speed to medium; gradually add 2 tablespoons of the granulated sugar, 1 tablespoon at a time, beating until soft peaks form. Increase speed to high; gradually add remaining 6 tablespoons granulated sugar and the powdered sugar, 1 tablespoon at a time, beating until stiff peaks form and sugar is dissolved, 2 to 4 minutes. Fold in chocolate extract and grated chocolate. Onto cookie sheets, drop meringue by rounded tablespoonfuls about 2 inches apart.