Place the broken chocolate and warm water in a large, heat proof bowl and sit it over a pan of barely simmering water until the melts. Remove from heat and stir thoroughly until the chocolate is smooth and glossy. Let the mixture cool before adding in the egg yolks. Immediately mix together using a wooden spoon. In a clean bowl, whisk the egg whites to soft peaks. Whisk in the sugar gradually, then continue whisking until the whites are glossy and meringue like. Next, use a metal spoon to fold the egg whites into the chocolate mixture. Divide the mousse equally between 5 ramekins and chill for at least two hours. Serve with a dollop of whipped cream.