Preheat the oven to 400F.
Place the flour, salt, and sugars in a large bowl and mix well. Taking a few cubes of butter at a time, rub into the flour mixture. Keep rubbing until the mixture resembles breadcrumbs, chill.
Combine apples, lemon juice, cinnamon, nutmeg, demerara sugar, and Brazil Nuts.
Butter an ovenproof dish. Spoon the fruit mixture into the bottom, then sprinkle the crumble mixture on top.
Bake in the oven for 30 minutes until the crumble got browned and the fruit mixture bubbling.
Serve with thick cream or custard.