Heat water in the bottom half of a double boiler over medium heat. Place semisweet chocolate in the top half of the double boiler. Allow the chocolate to melt slowly, about 9-10 minutes. Remove from heat and stir until smooth. Keep at room temperature until needed.
Chill the bowl and balloon whip for mixer. Place the cream in chilled bowl and whisk on high speed until peaks form, about one minute. Set aside.
Whisk 3 eggs in a large stainless-steel bowl until soft peaks form, about 3 minutes. Add sugar and combine to whisk until stiff peaks form, about 2-3 minutes. Add 1/4 of the whipped cream to the chocolate and whisk quickly, vigorously and thoroughly. Gently fold in egg whites, then add the remaining whipped cream. Fold all together gently but thoroughly. Refrigerate until served.