Preheat oven to 350. Peel, core and slice apples. Butter a 2 qt casserole dish and place apples in your dish. Mix cold water with cinnamon and cornstarch and pour over your apples.
In a bowl with a pastry blender combine sugar, flour and butter until crumbly. Sprinkle butter mixture over the apples. Bake uncovered for 45 minutes or until golden and filling is bubbling. This makes awesome ala mode!