Add the apples, cornstarch, sugar, water, and cinnamon to a 9x13-inch baking dish and toss well to combine. Drizzle with butter.
Cover with foil and bake for 20 minutes.
Uncover and stir the apples, bake uncovered for an additional 15 to 20 minutes or until the apples are tender.
Notes
Peeling is optional but we prefer the texture when the apples are peeled.Leftovers will keep in the refrigerator for 4 days and in the freezer for 3 months.