Beat the yolks of the eggs and the sugar until very, very light; fold in the whites of the eggs and the flavoring. Stand the bowl in a pan of boiling water and beat continuously until the ingredients are hot; take from the fire and beat constantly for ten minutes. When this is cool, fold in the cream whipped to a stiff froth, pack and freeze.
Serve with quince jelly sauce poured over the mousse.
This will serve eight persons.