Place cream and butter in a small saucepan and bring to the boil.
Once boiling, remove from the heat and immediately add the white chocolate, stirring until melted and smooth.
Mix in chopped cranberries and Cointreau, then refrigerate for 2-3 hours or until just firm.
Meanwhile, process the pistachio nuts very finely - about the size of dry breadcrumbs.
Roll the mixture into balls (about 2 tsp of mixture in each), then roll balls in pistachio crumbs.
Once balls are rolled in pistachio crumbs, roll each ball between your hands again to help the pistachio crumb stick well.
Refrigerate for 30 mins or until firm.