When I first learned to make chocolate truffles thirty years ago I didn't know I was learning the recipe originally conceived, or at least credited to, Fernand Point (1897-1955), one of the greatest French chefs. He trained or mentored such giants as Paul Bocuse, Alain Chapel, and Jean and Pierre Troisgros, which should give you a clear idea of just how great he was.
These are all that a chocolate truffle should be: simple, classic, elegant, easily varied. They are proof, if proof is needed, that less is more. I've varied the original recipe, as most chefs will, by allowing the use of a liqueur or espresso instead of water, and by the addition of a very small pinch of fleur de sel.
4 ounces bittersweet chocolate, chopped
3 ounces unsalted butter, cubed, at room temperature
1 egg yolk
1 tablespoon liqueur, espresso, or water
very small pinch fleur de sel
unsweetened cocoa powder
Put the chocolate into a heatproof mixing bowl or the top of a double boiler. Melt the chocolate over, but not in, simmering water, stirring continuously. When the chocolate is nearly melted, add the butter and continue to stir until incorporated. Remove the bowl from the hot water and mix in the egg yolk. When the yolk is fully incorporated, add the tablespoon of liqueur or water and the fleur de sel. Mix well, then cover tightly and refrigerate overnight.
Using whatever tool you prefer, make a small ball of chocolate. It does not need to be perfectly round. A quenelle is fine. Roundish is fine. If you feel it needs to be rounder, roll it quickly between your palms. Then carefully roll it with a fork on a plate covered with unsweetened cocoa powder. Repeat until you've finished making all the truffles. Chill briefly to set the truffle. Serve slightly chilled.
You may find that the truffle is too hard at first. Let it sit at room temperature a few minutes until it's soft enough to work. If you don't work quickly enough, the truffle might get too soft, making it difficult to form. In that case just refrigerate a few minutes until it's workable again.
I think my favorite variation is to use Chambord as the liqueur. If I don't want any alcohol at all in the truffle, then I might add some cinnamon to the cocoa powder and maybe just a teeny tiny pinch of chipotle powder to the truffle.
For me the biggest challenge is to let a "flawed" truffle go instead of eating it to hide the "mistake." That's one reason I can't tell you how many truffles this recipe will yield. I can only suggest that it will yield as many as you don't eat while making them.