This recipe does not work. There isn't enough cream to melt the chocolate, so I put the whole bowl over simmering water to actually melt it, left it in the fridge, and it was way too hard to even cut, much less form into balls. I didn't want to waste the chocolate so I did the double boiler thing again the next day with another tablespoon of cream. No luck. So after a few hours I added a second tablespoon of cream and one scant tablespoon of butter to soften and this was enough to roll.
There wasn't enough cream for this recipe. Even at room temperature the ganache was too hard. I had to warm it back up and add 1/4 cup more of cream. The ratio should be 2:1 for chocolate to cream, so for 12 oz of chocolate, make sure you have 6 oz of cream!