Wash and quarter apples, remove core. Cut apple quarters into thin slices. Mix apple slices, lemon juice and 2 tablespoons of sugar in a saucepan, cover and steam for about 3 minutes. Fill croissants and apples into an ovenproof dish. Whisk eggs and 6 tablespoons of milk. Mix sauce powder, 3 tablespoons of sugar and 6 tablespoons of milk until smooth.
Bring 380 ml of milk to the boil, stir in the mixed powder and boil for 1 minute. Stir in whisked eggs and spread on the croissants. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 15 minutes. Cover the casserole if necessary. Serve dusted with icing sugar. Cranberries taste good with it