Tuna Fish Casserole
This is the casserole I grew up on, and is still a family favorite. Although I replaced the Velveeta with a good cheddar many years ago, my sister admits she still adds "at least some" Velveeta. I'll issue a guilt-free pass on that one.
The amounts of everything here are really a matter of taste. Don't forget to taste while cooking, salting as necessary, so you don't end up with something bland.