First sprinkle a little salt on the aubergine and leave the slices to drain. Heat
Rinse the salt off the aubergine and pat dry. Fry the slices in the remaining oil and then drain on kitchen paper to remove as much of the oil as possible. Layer with the lamb in a wide ovenproof dish. Cover with the potato slices.
Melt the butter, stir in the flour and the nutmeg and lastly the warm milk. Allow it to thicken and then remove from the heat, season and stir in the egg yolks. Pour over the other ingredients.
Bake uncovered at