5 oz bittersweet chocolate
2 oz milk chocolate
1/2 cup heavy cream
2 tsp prepared coffee
1/2 tsp pure vanilla extract
Optional toppings: cocoa powder, confectioner's sugar, chopped walnuts, chopped pistachios
Cut the chocolate into fine pieces (a serrated knife works well for this), and place in a large heat-proof bowl. In a small saucepan, scald the cream, and pour it over the chocolate. Stir with a whisk until the chocolate melts and is smooth and glistening. Stir in the coffee and vanilla. (You've just made a ganache!) Cover the bowl with plastic wrap, and chill for several hours, until firm.
Place each desired topping in a small bowl or on a rimmed plate. With a small ice cream scoop, or two spoons, scrape off small blobs of the chilled ganache and form into rounds. They should be somewhat irregular and look like something a pig would sniff out of the ground (which, of course, is how chocolate truffles got their name). Gently roll each blob in one of the toppings, and place on a clean plate lined with parchment paper. Refrigerate for at least an hour, or longer. Serve slightly chilled.