Meanwhile, in 4-quart saucepan, mix sugar, raspberries and 1/4 cup sugar; bring to a boil over medium-high heat. Break up berries with spatula or wooden spoon if frozen together. Continue to cook 5 minutes, stirring frequently, until berries burst and mixture begins to boil vigorously. Combine cornstarch and 1/4 cup water in a small bowl. Stir into boiling mixture and continue to cook 2 minutes, or until mixture is very thick. Strain sauce through fine mesh strainer. Spoon 1/4 cup sauce over warm crescent ring. Serve with remaining sauce.