Line unpricked pie shell with a double thickness of heavy-duty foil. Bake at 450° for 8 minutes. Remove foil; bake 5 minutes longer. Cool on a wire rack. , In a large saucepan, combine sugar and cornstarch. Stir in the raspberries; bring to a boil over medium heat. Boil and stir for 2 minutes. Remove from the heat; cool for 15 minutes. Spread into shell; refrigerate. , In a large bowl, beat the cream cheese, sugar and vanilla until fluffy. Fold in whipped cream. Carefully spread over raspberry layer. Cover and refrigerate for at least 1 hour. , In a microwave, melt chocolate and butter; stir until smooth. , Cool for 4-5 minutes. Pour over filling. Cover and chill for at least 2 hours. Store in the refrigerator.