This is so very easy, and can be made ahead and reheated and tastes even better,. It goes especially well with turkey or chicken, and is festive enough for holday meals or easy ebough for weekday fare.
The bones of this recipe come from Saveur, because it is the simplest, purest version I've found yet. Feel free to go off the hip on cheese and butter amounts—most of this dish can just be cooked to taste. You can even—gasp—use another type of pasta if you wish.