To start, poke your potatoes with a fork so the steam can escape, and pop them in the oven for about an hour. You want them to cook up, and for the moisture to escape. Otherwise your dough will be sticky and heavy. Once they're out of the oven, peel them, and push them through a ricer, if you have one. We don't, so we just made sure there weren't any big lumps of potato.
This was a perfect dish for Oscar night, it had the glitz and glam of Hollywood from the truffle, and was hearty and comforting just like a night on the couch.