In a large mixing bowl, stir together the egg whites, the 1/2 teaspoon vanilla, and cream of tartar. Beat the mixture with an electric mixer on medium speed for about 1 minute or until soft peaks form (tips curl). Gradually add the 6 tablespoons sugar, 1 tablespoon at a time, beating on high speed for about 4 minutes more or until meringue mixture forms stiff, glossy peaks (tips stand straight) and all of the sugar dissolves.