Chop the chocolate finely. Bring the cream to a boil in a saucepan, then remove from the heat and stir in the chocolate until melted. Cool slightly and stir in the crème fraîche. Chill in the refrigerator for about 3 hours until firm but not hard.
With a small spoon scoop out cherry-sized portions and roll into balls between your hands. Roll the truffles in cocoa powder. Serve immediately or store in the refrigerator for up to a week.