1.Stir cream and chocolate in small saucepan over low heat until smooth. Stir in ginger.
2.Transfer chocolate mixture to small bowl. Cover and refrigerate 3 hours or overnight.
3.Working with a quarter of the chocolate mixture at a time (keeping remainder under refrigeration), roll rounded teaspoons into balls and place on a tray. Refrigerate truffles until firm.
4.Working quickly, roll truffles in sifted cocoa, return to tray; refrigerate truffles until firm.