Line a 9-in. pie plate with pastry; flute edges. Line unpricked pastry 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 small saucepan, combine the flour, cornstarch and 1/2 cup sugar. Add water and rhubarb; stir until blended. Bring to a boil; cook and stir for 2 minutes or until thickened. Remove from the heat; stir in 1/2 teaspoon vanilla. Transfer to prepared pastry.
In a small bowl, beat the cream cheese with remaining sugar and vanilla until smooth. Add eggs and egg yolk; beat on low speed just until combined. Spread over top of pie.
Cover edges with foil. Bake at 325° for 25-30 minutes or until set. Cool on a wire rack for 1 hour. Refrigerate for at least 4 hours before serving.