Pour the chocolate mixture into a pastry bag fitted with a 1-cm (1/4-inch) plain tip. Insert the tip of the pastry bag into the cheese mixture and squeeze out 15 to 30 ml (1 to 2 tablespoons) of chocolate mixture into the cheesecake batter. Repeat this around the cake with the remaining chocolate mixture. With a spoon, cover the chocolate smudges on the surface of the cheesecake with the plain mixture for a more uniform cheesecake or make dots with the remaining chocolate mixture on top of the cheesecake (see picture).