1. Preheat oven to 375°. Working with prepared dough, cut into edges with scissors at intersecting 45-degree angles to form pointed pieces of fringe. Freeze 10 minutes or until firm.
2. Line bottom of dough with foil; arrange pie weights on foil. Bake in middle of oven 20 minutes or until just set. Remove weights and foil; brush edges with egg white, and sprinkle with turbinado sugar. Return to oven; bake 10-15 minutes more. Transfer to a wire rack; let cool.
3. Turn oven up to 400°. Arrange grapes in 1 layer on an 18- x 13-inch baking pan. Bake in middle of oven 10 minutes or until grapes begin to release juices but are still intact. Transfer to a wire rack; let cool.
4. Whisk together mascarpone and next 3 ingredients (through vanilla) in a bowl until well-combined. Spread filling into cooled pie shell, and top with roasted grapes. Brush grapes with jam. Slice and serve.