APPLE FILLING:Pour milk or water, lemon juice, vanilla extract, ground cinnamon, ground nutmeg, brown sugar, pinch of salt, flour and butter in a medium bowl. Stir until it becomes smooth. Set aside.Peel the apples and cut them into thin slices. Place the apples in an 8x8 inch baking dish, coat them in the apple filling. Leave aside.TOPPING:Mix flour, rolled oats, baking powder, pinch of salt, ground cinnamon and brown sugar in a large bowl. Add chopped butter and stir well until it resembles small crumbs.Coat the apples with the mixture.Bake at 375F, for 25-30 minutes.