From this recipe I learned the correct ways to whip cream, to beat egg whites, and for melting chocolate. I'll share all of that later.
8 ounces (1 and 1/3 cup) sweet or semisweet baking chocolate, melted with 1/4 cup strong coffee (or hot chocolate)
3 ounces (6 Tbs) softened unsalted butter
3 egg yolks
1 cup heavy cream
3 egg whites
1/4 cup "instant" (finely ground) sugar (I used powdered sugar)
Optional accompaniment: whipped cream
Butter and egg yolks. Beat the soft butter into the smoothly melted chocolate. One by one, beat in the egg yolks.
The whipped cream. Beat the cream over the ice until it leaves light traces on the surface. (I used a chilled bowl the second time and it worked great.)
The egg whites. Beat the egg whites until they form soft peaks. While beating, sprinkle in the sugar by spoonfuls and continue beating until stiff shining peaks are formed.
Finishing. Scrape the chocolate mixture down the side of the egg-white bowl, and delicately fold them together. When almost blended fold in the whipped cream.
Chilling and serving. Turn the mousse into an attractive serving bowl, or into individual coupes or containers. Cover and chill several hours. You may which to decorate the mousse with swirls of whipped cream, or to pass whipped cream separately.