Here is my truffle recipe:
16oz. good quality dark chocolate
3/4 cup heavy cream
1 cup (two sticks) unsalted butter
good quality cocoa powder or confectioner's sugar
Chop up the chocolate. In a double boiler (I use a pyrex dish on top of a pan of water), melt the chocolate together with the cream. Do this slowly over medium heat, stirring regularly.
When the chocolate and cream are completely mixed and melted together, take them off the heat and add the butter. Stir until the butter is completely incorporated. It helps a lot to chop the butter up into smaller pieces before adding it.
When it is all melted and mixed, put the mixture in the fridge for at least 6 hours.
When it is nice and cold, take a really small ice cream scoop* (I think mine is 1/4 oz) and scoop out round balls of the mixture. Roll them a bit in your hands to make them round and drop them in a dish of cocoa powder (or the confectioner's sugar if you like them sweeter). Roll them to cover them in the cocoa powder and they are done.
Keep them refrigerated. They keep about two weeks. You generally don't have to worry about them going bad.
*You may wonder whether you really need the ice cream scoop. I tried making them without it the first time, and frankly, they ended up looking like little chocolate turds. The effect was really unappetizing, though I think I laughed for about half an hour when I realized what they looked like.