Preheat the oven to 200C, Fan 180, Gas Mark 6

Peel, core and chop the apples into small pieces

Add the apples to a pan with the caster sugar, vanilla essence and water.

Cook on a low heat for a few minutes until the apples soften. Check the taste and add a little more sugar if required

Put the apples into an oven proof dish

Add the flour, demerera sugar and butter into a mixing bowl.

Run the butter into the flour until it resembles breadcrumbs

Stir in the oats

Scatter the crumble topping over the apples in a dish and sprinkle on some sugar.

Bake for 40-50 minutes until golden.

Serve with ice cream or custard.