Place the chocolate and cream in a heatproof bowl over a saucepan of simmering water (make sure the bowl doesn’t touch the water). Use a metal spoon to stir until melted and the mixture is smooth. Stir in vanilla, if using. Set aside to cool slightly.
Stir in the cranberries and pistachios. Refrigerate for about 3 hours, stirring occasionally, or until firm enough to roll into balls (the mixture will still be a bit sticky).
Place coconut in a shallow dish. Roll level tablespoons of mixture into balls and roll in coconut. Arrange in a single layer in an airtight container and keep in the fridge until ready to serve.
