In a small saucepan over medium heat, bring the heavy cream, vanilla, chili, cinnamon stick and cloves just to a boil. Turn off the heat, cover and steep for 30 minutes.
Strain the solids from the cream, return the cream to the saucepan and bring just to a boil again. Remove from the heat immediately.
Add the chopped chocolate and butter and stir until the mixture is completely smooth (this mixture is called ganache). Chill the ganache until it is hard enough to roll into balls.
Measure out by heaping teaspoons, and quickly roll the ganache into 1- to 2-inch balls and place on a wire rack. Refrigerate the chocolate balls until firm, then pour melted dark chocolate over them to coat. Refrigerate until firm. Chocolate truffles should be kept in the refrigerator in a tightly sealed container. To serve, bring to room temperature.