Break up the chocolate and place in a heatproof bowl with the water. Slowly melt it, stirring regularly. When the mixture is smooth, leave it aside to cool for a few mins.
Meanwhile, whisk the egg whites until they form soft peaks.
Whisk the sugar into the egg whites about a third at a time.
Stir the egg yolks into the chocolate mixture.
Using a metal spoon, fold a small amount of the egg whites into the chocolate mixture. Then gently fold in the rest.
Divide the mixture equally between the glasses and chill for a couple of hours.
