After ganaching a cake, I sometime have left over ganache that I don’t want to throw away. Its usually only a few tablespoons so I make little home made truffles with them. Ganache also freezes very well and can sit at room temperature for a few days, or so I heard from a Chocolatier.
A firm ganache is exactly what truffles are, and if you use a good quality dark chocolate they’ll taste just as good (if not better) then what you can get from the shops. So when you have some firm 2:1 chocolate ganache left over, just scoop, roll in cocoa powder and eat.