Take two large cooking apples. Peel the apples and slice them and ad granulated sugar.
Mix 1oz granulated sugar, 1oz Demerara sugar, and 4oz flour. Add the butter. Use your hands to rub it in. Continue until mixture is lumpy - do not make it too firm.
Place the crumble on top of the apples. Sprinkle a tablespoon of Demerara sugar on top.
Bake in a pre-heated oven at about 350F (175C)
Remove from the oven after 30-40 minutes (when brown)