Leave the aubergines unpeeled and slice them. Sprinkle with cooking salt and leave in a colander for about 1 hour to draw the juices, with a plate pressed down on top. Rinse in cold water and pat dry. Fry the aubergine slices in plenty of oil in a large frying pan. Turn to brown them on both sides before removing them from the pan.
Peel and slice the onions and fry in about
Arrange layers of meat mixture and aubergines in an earthenware ovenproof dish, ending with a layer of aubergines. Set aside while preparing the topping.
Melt the butter over low heat and stir in the flour. Cook gently for a few minutes, then gradually stir in the milk. Bring up to the boil, beating well to get a smooth sauce. Season with salt and pepper and simmer for 1–2 minutes. Draw off the heat and beat in the egg – the addition of egg helps to form a topping that remains on the surface of the moussaka.
Pour the topping over the moussaka. Place in the centre of a moderately hot oven (190°C., 375°F., Gas Mark 5) and cook for 45 minutes-1 hour when the top should be golden brown. Serve hot or cold with salad.