Peel and core the apples and cut into pieces. Put into a pot together with the whiskey, brown sugar and lemon and simmer for 5 to 10 minutes. Mix sugar, nuts, flour, salt and nutmeg in a big bowl. Cut up and add cold butter and knead with your hands until no more lumps of butter are visible.
Put the steamed apples into a baking pan and spread with the crumbles.
Spread the chopped hazelnuts and bake golden-brown at 180° for 40 minutes.