Melt the chocolate in the microwave and stir in the butter piece by piece until it is all melted.
Add the chestnut cream and mix well.
Line a loaf pan with waxed paper and pour the mixture into pan, making sure it fills the pan to the edges. Place overnight in the refrigerator.
To serve: remove from pan and place on serving plate. Using a fork trace lines to give the appearance of a log. Decorate with powdered sugar.
6 to 8 servings
Note: There's nothing to stop you from using this French yule log recipe in other ways. Try molding the cake in miniature cake molds for a fabulous treat anytime of the year.