Preheat the oven to 180°c (160 fan/ Gas 4/ 350F).
Make the crumble topping by pouring melted butter onto the flour, oats and light brown sugar. Mix with a spoon until crumbles form.
125 g Plain Flour, 125 g Rolled Oats, 125 g Unsalted Butter, 125 g Light Brown Sugar
Peel and thinly slice the apples, and mix with the cinnamon, caster sugar, and water in a 2 litre pie dish.
6 Bramley Apples, 50 g Caster Sugar, 2 teaspoon Ground Cinnamon, 2 tablespoon Water
Spoon over the crumble topping and bake in the oven for 35-45 minutes until golden and the fruit underneath bubbling. Allow to cool for 10 minutes before serving.