Stir together all the apple filling ingredients in a large bowl until well combined. Dump into the prepared baking dish.
Add the oat crisp topping to the large bowl. Mix with your fingers, breaking up the curds of cottage cheese until they are incorporated into the topping. Sprinkle on top of the apple filling.
Bake for 45 min until golden brown with the juices thickened and bubbling along the edges.