Unfold 1 piecrust, and roll into a 16-inch circle on a lightly floured surface; cut into 4 (5 1/2-inch) circles. Fit each circle into a 4 1/2-inch round tart pan with removable bottom, and place pans on a baking sheet. Prick bottom and sides of pastry with a fork. Repeat procedure with remaining piecrust.
Bake at 450° for 8 minutes or until lightly browned. Remove tart shells to wire racks to cool.
Cook sugar, flour, and Scuppernong Juice in a medium saucepan over medium heat, whisking constantly, until mixture coats back of a spoon (about 5 minutes). Remove from heat; stir in butter and vanilla. Spoon about 1/3 cup mixture into each tart shell; cover and chill. Dollop with sweetened whipped cream. Garnish, if desired.