1) Preheat oven to 375 degrees F. In a large saucepan combine cherries, sugar, flour and 3 tablespoons water. Cook and stir over medium-low heat until cherries are thawed and juices thicken. Gently stir in raspberries and vanilla.
2) Line a 9-inch pie plate with half the pastry. Spoon fruit mixture into pastry-lined pie plate. Trim crust even with edge of pie plate.
3) Brush edge of crust with a little water. Top with remaining crust. Turn under edges and crimp to seal. Brush crust with milk and sprinkle with sugar, if desired. Cut slits in top crust to allow steam to escape.
4) Bake for 45 to 50 minutes or until crust is golden and filling bubbles in center. Cool on wire rack. Serve with ice cream of whipped cream if desired.