Preheat the air fryer to 170°C (320°F) and butter a 1.5 litre baking dish. The shape of the dish can vary depending on the size and shape of your particular air fryer. It's important to note that any dish that is safe to use in an oven can also be used in an air fryer.
Place the flour, oats, and brown sugar in a mixing bowl and stir in the melted butter until crumbles form. Set aside.
100 g Plain Flour, 100 g Oats, 100 g Light Brown Sugar, 100 g Butter
Peel and thinly slice the apples and place them into the baking dish with the caster sugar, cinnamon, and water. Give it a mix and then air fry for 12-15 minutes until the apples have softened.
700 g Bramley Apples, 25 g Caster Sugar, ½ teaspoon Cinnamon, 1½ tablespoon Water
Sprinkle over the crumble topping and air fry for a further 15-20 minutes until the top is golden and the fruit is bubbling underneath. Allow to cool for 10 minutes before serving.