Heat the cream until it just comes to a boil, add the chopped chocolate and remove pan from heat.
Stir or whisk until the chocolate is completely melted.
Only for milk or dark truffles: Stir in the butter until the ganache is smooth.
Put in a bowl and cover with plastic wrap ensuring that the plastic makes
contact with the entire surface of the ganache.
Refrigerate over night or until the ganache is set.