Toss apples with filling ingredients. Transfer to a greased baking dish.
Mix first four topping ingredients. Fold in butter with hands until crumbly, and sprinkle over filling. Add more butter as needed (topping should be in crumbles).
Sprinkle brown sugar on top.
Bake for 25-30 minutes until topping is golden.
Serve with a scoop of vanilla ice cream for dessert - or with some yogurt for breakfast!