I'm having a problem with my truffles becoming too soft on the inside after dipping and refrigerating. I use cream and butter to make them, flavor them with liquor or extracts. I've read the ganache shouldn't be placed in the fridge. I leave mine out until it cools and then refrigerate it because I don't normally dip it the same day. It's firm out of the fridge but leave out a bit or coat it and try to bite into one, it's very soft. I want it to be harder at room temp. Any ideas? I see some people don't use butter at all. Is that my mistake?