Here is the chocolate mousse recipe I used. I've just copied and pasted from the Epicurious website, but I'll also post a link in case you'd like to take a look. I also thought I'd post a photo of how mine turned out! Please, please pardon the terrible photo quality. My camera is dying, almost dead. Poor, poor camera!
Regarding the recipe, bittersweet chocolate is typically considered anything between 60-72% cocoa. The bar I used was 85%, so I added a fudge more sugar than called for.
DARK CHOCOLATE MOUSSE
Mousse au Chocolat Noir
Chocolate mousse is a standard bistro dessert, in part because it's so easy and quick to serve. Here it is in its classic form: chocolate and butter melted together, cooled slightly, and combined with egg yolks; then whipped cream and sweetened egg whites are gently folded into the mixture.
In France, they would serve chocolate mousse from a big bowl, scooped onto a plate with some cookies. At Bouchon, we serve it in lidded pot de crème molds with langues de chat cookies.
4 1/2 ounces bittersweet chocolate, finely chopped
2 tablespoons (1 ounce) unsalted butter, diced
2 tablespoons espresso or hot water
1 cup cold heavy cream
3 large eggs, separated
1 tablespoon sugar
Combine the chocolate, butter, and espresso in the top of a double boiler over hot, but not simmering, water, stirring frequently until smooth. Remove from the heat and let cool until the chocolate is just slightly warmer than body temperature. To test, dab some chocolate on your bottom lip. It should feel warm. If it is too cool, the mixture will seize when the other ingredients are added.
Meanwhile, whip the cream to soft peaks, then refrigerate. Once the melted chocolate has cooled slightly, whip the egg whites in a medium bowl until they are foamy and beginning to hold a shape. Sprinkle in the sugar and beat until soft peaks form.
When the chocolate has reached the proper temperature, stir in the yolks. Gently stir in about one-third of the whipped cream. Fold in half the whites just until incorporated, then fold in the remaining whites, and finally the remaining whipped cream.
Spoon or pipe the mousse into a serving bowl or individual dishes. Refrigerate for at least 8 hours. (The mousse can be refrigerated for up to a day.) Makes 8 servings.