Sugarless apple pie

1 Pastry for 9" double crust
1 can frozen apple juice concentrate (6 oz)
3/4 teaspoon Cinnamon
3 c Apple slices
1 tablespoon Cornstarch
2 T Water
1 1/2 tablespoons Margarine

Roll out half of the pastry to fit a 9" pie plate. Fit into pie pan and trim pastry 1 inch beyond rim of pie pan. Heat undiluted apple-juice concentrate and cinnamon in a large saucepan. Add the apple slices and cook until partly tender. Remove apple slices. Mix cornstarch and water until smooth. Add to juice in saucepan and cook, stirring constantly, until thick. Combine apples and sauce. Cool slightly. Fill unbaked pastry shell and dot top of fruit with margarine. Roll out remaining pastry and fit over top. Trim pastry 1 inch beyond the rim of pie pan. Fold edges under and flute. Cut vents in top of pastry. Bake in a preheated 375 degree oven 45 minutes until golden brown.