Preheat oven to 350˚F.
Stir apples, corn starch, cinnamon and corn syrup together in a large bowl, until apples are well coated. Transfer to a greased 8 x 8-inch baking dish.
Combine oats, brown sugar and flour in a large bowl. Cut in butter with a pastry blender or two forks until mixture is crumbly. Sprinkle over apples.
Bake for 45 to 60 minutes, or until apples are tender.