Bring the milk to boiling point and remove from the hob. Break up the chocolate and dissolve in the milk. Briefly beat the eggs, the egg yolk and the sugar.Wash the orange in hot water, and dry. Grate half of the orange zest finely into the creamed egg mixture, followed by the hot chocolate milk. Preheat the oven to 160 °C. Boil the water.
Butter 4 ovenproof timbale or soufflé moulds. Pour the mixture into the buttered oven-proof moulds. Cover with aluminium foil. Place inside an ovenproof dish. Pour boiling water into the dish up to two thirds the height of the moulds. Place in the centre of the oven to poach for 30-40 minutes (the time depends on the diameter of the moulds). Remove from the oven and allow to cool. Place in a cool place for at least 3 hours.
Remove the remaining orange peel in strips. Blanch the strips in boiling water. Drain, then pour cold water onto the strips. Remove the rest of the orange peel to reveal the flesh, cut the fruit into tiny dice.
For the sauce, just before serving, break up the plain chocolate. Dissolve it with the cream in a hot bain marie. Turn the toppers out onto a plate. Decorate with the chocolate sauce, the cubes of orange and the zests. Serve immediately.
HINT. Add a decoration of chocolate curls: Place some melted Edelbitter plain chocolate onto a cold marble slab, roll it out smooth and, when dry, use a spatula to prise it from the board so that it curls into a little roll.