Pre-chill six serving vessels, two large-ish bowls, and balloon whip/egg beater thingies.
Heat one inch of water in the bottom half of a double boiler over medium heat. Place chocolate in top half. Tightly cover top half with plastic wrap. Allow the chocolate to melt slowly, about 9-10 minutes. Remove from the heat. Stir until smooth, and keep at room temperature until needed.
Place 1 1/2 cups heavy whipping cream in a chilled bowl. Whip with a chilled balloon whip until peaks form (about 1 minute). Set aside until needed.
Whisk 3 egg whites in a large stainless-steel bowl until soft peaks form (about 3 minutes). Add sugar, and continue to whisk until stiff peaks form (about 2-2 1/2 minutes).
Add 1/4 of the whipped cream to the chocolate, and whisk quickly & vigorously.
Gently blend in the egg whites. Gently fold in the remaining whipped cream.
Put in vessels and refridgerate.