I obtained this recipe from an out-of-print French cookbook.
Chocolate Mousse
Preparation: 15 to 18 minutes
Cooking time: 4 to 5 minutes
For 6 people:
-- 200 g very good quality and slightly bitter chocolate (it exists in the trade as special dessert chocolate)
-- 150 grams of powdered sugar
-- 4 eggs + 1 white
-- 1 tablespoon rum
-- ¼-½ cup of very strong coffee
Break chocolate into very small pieces, put it in a large pot (you will need to add the well- beaten egg whites [in French, known as “snowy eggs” because of their white color], it is necessary to provide a pan of sufficient size), add coffee, and put in a bain-marie or in a hot oven to soften the chocolate, and when it is pasty, add the rum, mix well to get a thick and smooth cream.
Break the eggs and separate whites from yellows, add the yolks to the chocolate cream, mix thoroughly.
Beat all the egg whites into a firm, fluffy white snow, gradually incorporating the powdered sugar.
Very delicately add the egg whites to the chocolate cream.
Pour into bowls, and put in the refrigerator until ready to serve.
Tip: You can replace the rum with two tablespoons of orange-based liqueur (triple sec) and incorporate into the chocolate mousse chopped orange peel comfit.
Obtained from:
Buteux, Paulette. La cuisine toute simple. Éditions Stock, 1973.