The crumble can be assembled 1 day ahead. Cover with plastic wrap and store in the refrigerator until needed. Bake as directed in recipe, but allowing extra 5 to 10 minutes cooking time and check crumble is piping hot in the centre. Crumble topping can be made and frozen in resealable plastic bags, for up to 3 months. Sprinkle topping direct from freezer over fruit, breaking up large lumps with your hands. The assembled but unbaked crumble can be frozen, wrapped in a double layer of plastic wrap and a layer of aluminum foil, for up to 3 months. Defrost for 24 hours in fridge and bake as above.