For this recipe you will need 6 glasses. Start by placing a piece of sponge in the bottom of each glass. Soak each piece with a little of the liqueur. To prepare the custard, place the water and milk in a saucepan and heat together gently. Remove 3 tablespoons of the liquid from the pan whilst still cold and place in a small bowl. Add in the corn flour, egg yolks, orange zest and vanilla essence and stir to a smooth paste. When the milk and water mixture reaches boiling point, quickly whisk in the egg mixture and mix till you have smooth custard. Turn off the heat, and pour half the vanilla custard into the glasses. Quickly add the dark chocolate to the remaining vanilla custard, and mix together to melt the chocolate and produce the chocolate custard. Quickly place another piece of sponge on top of the vanilla custard in the glasses and carefully pour over the remaining chocolate custard. Allow the custard to cool slightly for 5 minutes before placing the glasses in the fridge for 30 minutes for the custard to set. When you are ready to serve the vanilla and chocolate custard soufflés, remove the glasses from the fridge and decorate the top of each soufflé with a piping of whipped cream, chocolate pieces and berries.