Use a glass serving dish or, if you want a high-rising crown, use a soufflé dish (about 500ml(1pt) capacity) and prepare in the following way: cut a 10cm (4 inch) wide double strip of waxed or grease proof paper, or cooking parchment or buttered foil. Secure it around the top of the dish with tape or string.
Melt the chocolate with the water to form a thick cream. Whisk the eggs, egg yolks and sugar together in a basin over hot water until thick. Remove from the heat and continue to whisk until the basin is cold. Then add the warm chocolate and the marmalade.
Dissolve the gelatine in hot water and add to the mousse. Stir until blended and thick. Fold in the whipped cream.
Turn at once into the glass serving dish or the prepared soufflé dish.