The fiery result was “the drink of the kings,” says Jean-Marc Gorce, a former French chef and co-founder of XOX Truffles Inc. in San Francisco. Gorce is one of many U.S.-based chocolatiers reviving the ancient custom of spicy confections. … New York City’s own spice master, Jacques Torres, was inspired to add heat to chocolate after a pilgrimage to Oaxaca, Mexico. His famous Wicked Hot Chocolate is a nod to the original south-of-the-border chocolate recipe—and just …