Make your ganache by heating the cream in a medium saucepan (or a microwavew safe bowl) to where it is starting to steam. Remove the pan from the heat and put in the chocolate, chopped into small pieces. Let this sit for about 5 minutes and then stir. If the chips are melted enough, keep stirring until smooth and blended. If not, wait a few more minutes. If still not melted, place back on stove over low heat stirring constantly until blended. Let cool. The ganache needs to be soft enough to pour over the roll, but not hot. If it gets too stiff, warm the bowl by wrapping it in a towel that has been wet with hot water and wrung out well. (DO not get water in the ganache) Alternately, you may briefly chill the ganache and spread it over the roll with an offset spatula. This method will give you a more rustic look and is suitable for Yule Logs.