In a large bowl stir together granulated sugar and cornstarch. Add frozen cherries and vanilla; toss gently to coat. Let mixture stand about 1 hour or until a syrup forms, stirring occasionally.
Meanwhile, preheat oven to 375 degrees F. On a lightly floured surface, use your hands to slightly flatten one ball of the Pastry for Double-Crust Pie. Using a rolling pin, roll pastry from center to edge into a circle about 12 inches in diameter. Wrap pastry circle around the rolling pin. Unroll pastry into a 9-inch pie plate. Ease pastry into pie plate without stretching it. Sprinkle 1/2 cup of the almonds into pastry-lined pie plate. Stir sweet cherry mixture; spoon over almonds. Top with pie filling, spreading evenly. Trim pastry even with pie plate rim.
Roll the remaining pastry ball into a 12-inch-diameter circle. Using a sharp knife, cut slits in pastry to allow steam to escape. Place pastry circle on filling; trim to 1/2 inch beyond edge of pie plate. Fold top pastry edge under bottom pastry. Crimp edge as desired.
Cover edge of pie loosely with foil. Place pie on middle oven rack. Line a baking sheet with foil; place on bottom rack to catch any drips. Bake for 50 minutes. Remove foil from pie. Bake about 30 minutes more or until pastry is golden brown and filling is bubbly. Cool on a wire rack for 1 to 1 1/2 hours.
In a small bowl stir together powdered sugar and enough of the milk to make a glaze of drizzling consistency. Drizzle glaze over pie. If desired, sprinkle with the 1/4 cup sliced almonds. Cool completely.
Pastry for Double-Crust Pie
In a large bowl stir together flour and salt. Using a pastry blender, cut in shortening and butter until pieces are pea-size, Sprinkle 1 tablespoon ice water over part of the flour mixture; toss gently with a fork. Push moistened dough to side of bowl. Repeat with additional ice water, 1 tablespoon at a time, until all of the flour mixture is moistened. Gather mixture inot a ball, kneading gently until it holds together.