Chop chocolate chips in food processor. Heat cream, butter and sugar in sauce pan or in the microwave until butter melts and mixture is near boiling. With the food processor on, slowly add the cream mixture to the chocolate and then add liquor. Beat until very smooth. Scrape mixture into a container and refrigerate until very firm (overnight). Roll mixture into balls. Coat your hands with powdered sugar or cocoa to prevent sticking. The balls may be frozen and later dipped in melted chocolate or rolled in chopped nuts. If the truffles are not dipped in chocolate, they will need to be kept refrigerated as they are quite soft.