1. Place the chocolate in a 1-quart bowl; then place the bowl in a 1-quart saucepan filled halfway with hot but not boiling water. Over low heat, melt the chocolate and stir to remove any lumps.
2. Remove the bowl of chocolate from the hot water bath.
3. Cut the butter into 4 pieces and gradually whisk it in, one piece at a time, until all the butter has been incorporated.
Whisk in the yolks until they're thoroughly combined. (Don't be concerned about the mixture looking grainy and separated or about using raw yolks; the yolks will essentially be "cooked" by the alcohol in the liqueur.) Then whisk in the cognac or other flavoring.
4. Cover and refrigerate for an hour, or until the mixture is firm but not rock hard.
5. Working quickly so that your hands do not melt the truffles, place a heaping teaspoon of chocolate in your hand. Press a dried cherry (or other fruit) into the center of the chocolate, and then shape the chocolate into a rough ball, about an inch in diameter, which completely encases the fruit. Handle the chocolate as little as possible to prevent melting.
7. Using your fingertips only, roll the truffle in cocoa. Place on a plastic wrap-lined plate, cover with additional wrap, and refrigerate until firm (about 30 minutes for dark chocolate and 15 minutes longer for milk or white chocolate). Your traditional truffles are now ready to eat!
8. To create "coins," wrap the truffles in gold or aluminum foil.
Tina Wasserman is the food editor of ReformJudaism.org and her books are available on her website. Reprinted with permission.