1) In a medium-sized saucepan or microwave safe container, heat the cream to boiling. Boil for 30 seconds to evaporate some of the water in the milk.
2) Remove from the heat and carefully add the chocolate. Let sit for 1 to 2 minutes to soften and melt. Add the vanilla if using.
3) Whisk the chocolate and cream together until smooth, silky and creamy. This mixture is called ganache.
4) Pour the ganache into a shallow baking dish or pan and refrigerate until firm, the consistency of soft clay. This will take about 1 to 2 hours.
5) To form the truffles, scoop small 3/4" balls from the chilled ganache. Roll each ball between the palms until rounded, but not perfectly so. The heat of your hands will slightly soften the truffle as you roll.
6) Roll the now softened truffle in your choice of toppings. Unsweetened cocoa, shredded coconut, chocolate sprinkles, toasted nuts and even sea salt are popular toppings.
7) Set the truffles aside to firm up before serving at room temperature. Truffles can be stored in the refrigerator for up to two weeks.