Luscious Chocolate Mousse

January probably isn't the best time to post a recipe for a rich, luscious chocolate mousse as a lot of us are trying to work off all the goodies consumed during the holidays. But I made this mousse for dessert for Christmas and it's a winner. Not overly sweet, terribly rich. Super easy. Because this mousse is fairly firm, it would also make a good filling for a genoise roll or a chocolate sponge cake.