1. In the top of a double boiler, melt the butter over moderate heat. Set the pan over barely simmering (not boiling) water and stir the coffee into the butter.
2. Beating constantly with a wire whisk or large spoon, sift in the cocoa, about ¼ cup at a time, and beat until the mixture becomes a smooth paste. Reduce the heat to the lowest possible point and keep the cocoa paste warm.
3. In a deep bowl, beat the egg yolks with an electric or rotarybeater for about a minute. Beat in the sugar, ¼ cup at a time, and continue beating until the yolks become pale yellow and thick enough to fall back in a ribbon when the beater is lifted from the bowl. Beat in the cocoa paste, about ½ cup at a time, then the liqueur. Set aside.
4. In a separate large bowl, with a wire whisk or a rotary or electric beater, beat the egg whites and salt together until the whites are stiff enough to stand in firm, unwavering peaks when the beater is lifted from the bowl.
5. Stir about one quarter of the whites into the cocoa-and-egg-yolk mixture, then pour it over the remaining egg whites. Gently but thoroughly fold them together, using an over-under cutting motion rather than a stirring motion.
6. Ladle the Pitch Lake pudding into a 1-quart souffle dish, a large serving bowl, or eight individual dessert dishes and refrigerate for at least 3 hours, or until thoroughly chilled.
7. Just before serving, spread the whipped cream lightly over the pudding, or, if you prefer, spoon the whipped cream into a bowl and present it separately.
