Preheat the oven to 200C/400F/Gas 6.
Butter 6 small ovenproof soufflé dishes or ramekins, each large enough to take 200-300ml (1/3-½ pint) and dust with caster sugar.
Put the cream, orange zest and juice into a saucepan large enough to take the chocolate, and bring up to the boil.
Tip the chocolate in, then draw off the heat and stir until melted.
Now stir in the sugar, then the egg yolks, one at a time.
Whisk the egg whites with the salt until stiff. Fold into the chocolate sauce.
Pour into the prepared soufflé dishes, then slide them straight into the freezer (covered with cling film) or into the hot oven.
Bake for 15-20 minutes (for unfrozen) or 20-25 minutes (for frozen) until well risen.
Dust with icing sugar and serve at once with some whipped cream, mixed with a few splashes of Grand Marnier.