Marinate coarsely chopped crystallised fruits in cognac for at least 2 hours. Beat egg yolks, flour and sugar together in the top of a double saucepan. Add the cream. Place over hot water and cook, stirring constantly, until thick and smooth. Do not allow to come to a boil. Stir in vanilla extract and Grand Marnier. Allow to cool, stirring occasionally.
Beat the egg whites and salt unti