Combine the chocolate and water in a heatproof bowl set over a pan of barely simmering water. Heat until the chocolate is almost completely melted, stirring occasionally. Remove the bowl from the heat and stir until the mixture is smooth. Set aside and let cool to near room temperature.

In a clean, dry bowl of a stand mixer fitted with the whisk attachment, combine the egg whites and the salt. Whip on medium-high speed until stiff peaks form. They should be thick and smooth.

Stir the egg yolks into the cooled chocolate mixture. Add one third of the whipped egg whites to the bowl with the chocolate and fold gently to lighten up the mixture. Fold in the remaining egg whites gently with a spatula just until no visible streaks are left.

Portion the mixture into 4 individual serving dishes (or 2 larger serving dishes, for a romantic, share-friendly dessert). Cover with plastic wrap and refrigerate at least 3 hours. Serve with freshly whipped cream and chocolate shavings, if desired.