Preheat the oven to 180C/350F/Gas 4. Grease and line a 20cm/8in springform cake tin. Wrap the outside of the cake tin in two layers of aluminium foil so that it will be waterproof when placed in the bain-marie in the oven.
In a bowl beat together the egg yolks with two thirds of the sugar until creamy.
Add the orange liqueur and beat for a further three minutes.
Stir in the melted chocolate and half of the cream.
In a separate bowl, whip the cream, then fold this into the mix.
In a clean bowl, whisk the egg whites until stiff peaks form when the whisk is removed. Beat in the rest of the sugar, then fold this into the chocolate mix.
Spoon the mixture into the lined, foil-wrapped cake tin and place into a deep baking tray. Set the baking tray onto the oven shelf. Half fill the tray with boiling water from the kettle to make a bain-marie.
Place in the oven for 45 minutes at 180C/350F/Gas 4 and then reduce the temperature to 150C/300F/Gas 2 for 45 minutes more.
Turn the oven off but leave the cake in for another 20 minutes.
Remove from the oven and allow to cool completely. Remove the cake from the tin and peel off the paper. Serve with fruit and cream.