Roll half of pastry to 1/8-inch thickness on a lightly floured surface; fit into a 9-inch pie plate. Set aside. Chill remaining pastry.
Combine sugar and flour in a medium saucepan, mixing well. Add water; bring to a boil. Reduce heat; cook, stirring constantly, until thickened. Stir in cranberries, butter, and vanilla, mixing well. Spoon mixture evenly into pastry shell.
Roll remaining pastry to 1/8- inch thickness; cut into 3/4-inchwide strips, and arrange in a lattice design over filling. Seal and flute edges. Bake at 350° for 35 minutes or until browned.