Use 1 egg and 55g choc per person, so for 2 people it would be:
4oz (110g) plain chocolate 2 eggs, seperated
Melt chocolate in a bowl over a saucepan of boiling water. When it is all smooth and melted, add the egg yolks, beating thoroughly (this cooks the eggs a bit). Leave to cool 15mins. Beat egg whites until they form soft peaks, then fold into the chocolate mixture. Put into individual glasses and chill for 2 hours.
If you want you can make a few holes in the top with a cocktail stick and spoon in some rum or brandy. Dollop of double cream on top goes down well