Put the mixing bowl into the freezer or refrigerator a few minutes before using so the bowl is cold.
Chop the chocolate then add to a double boiler at a low simmer. Stir chocolate with a heat-safe spoon until melted. Turn off the heat and let stand. Set aside.
Beat the cream in the chilled bowl until it forms soft peaks. Set aside and hold at room temperature.
With a mixer, whip egg whites to soft peaks. Gradually add the sugar and vanilla and continue whipping until firm.
Using a whisk, fold the egg whites into the chocolate. When fully incorporated, fold in the whipped cream.
Cover the mousse and refrigerate until set, at least one hour.
Wet the edges of the serving dishes and place gold flakes with tweezers, or gently place torn pieces of gold leaf in the center of each dish of mousse.