Drain the cherries and reserve the juice from only one can.
In a saucepan, stir the cherry juice into the combined mixture of the cornstarch and sugar. Cook over medium heat, stirring constantly until thickened.
Remove from heat. Gently stir in cherries and almond extract.
Pour filling into pastry lined pie pan (see pastry/pie crust recipe below). Dot with butter or margarine.
Gently roll top crust over pie, adjust crust, seal and vent.
Bake 30-40 minutes or until crust browns and filling begins to bubble. If necessary, cover edges with aluminum foil during last 15 minutes to prevent over-browning. Cool pie several hours to allow filling to thicken before slicing.
For the pastry:
Mix flour and salt in a large mixing bowl. With a pastry blender, cut in shortening until it resembles coarse crumbs.
Mix in the ice water, one tablespoon at a time, until dough forms a ball. Do not overmix.
Divide dough into two balls. Using a well-floured surface and rolling pin, roll each pastry ball from the center to the edges with long, even strokes.
Roll each pastry into a circle large enough to fit in a 9-inch pie plate.