Preheat the oven to 190°C (375°F) (gas 5)
Peel and core the apples. Slice them fairly thinly and place in a bowl with the sugar. Toss to coat the apples with the sugar and then spread over the base of the ovenproof dish.
Mix together the first four ingredients of the topping.
Pour the butter over the top and mix in until the mixture has become crumbly.
Sprinkle evenly over the apples.
Bake for 30 minutes or until the apples are tender and the juices are bubbling around the edge.
Best served with ice cream or whipped cream.