Preheat the oven to 350 F and oil the baking dish.
Mix brown sugar, flour, oats, cinnamon and salt. Combine with diced butter and grind until crisp texture. Put in the refrigerator.
Peel apples and dice.
Combine the melted butter, sugar, water, flour, cinnamon and nutmeg. Beat with a whisk, pour over apples and mix everything.
Put the apples in a prepared dish, and sprinkle with a mixture of oatmeal on top. Bake it in the oven 30-40 minutes until golden. Cool before serving.