Method
Preheat an oven to 200C, gas mark 6. Deseed the vanilla pod and add to the milk. Peel, core and quarter the apple. Gently heat the butter in a large frying pan, add the slices of apple, cinnamon and muscovado sugar. Cook over a high heat for 5 minutes, until the apple is lightly browned. Remove the cinnamon stick. Transfer the apple and all of the juices to a large ovenproof dish. Make sure the apple pieces sit in a single layer. Beat the eggs in a bowl. Add the castor sugar and beat until pale and voluminous. Whisk in the flour. milk and a pinch of salt. Add the milk. Pour the whisked mixture over the apples. Place the dish on a baking tray and cook for 30 minutes until puffed, golden brown and just set. Dust with icing sugar. Serve with whipped cream or ice cream.