Tuna Casserole

Cook macaroni until el dente' and drain.
Edited instruction, courtesy of Charlotte M., I think you Have to saute' the onions and celery first if you don't want a crunchy casserole, so much better sautee'd in butter, canola or olive oil.
Combine all ingredients.
Pour into baking dish.
Mix topping and put on casserole.
Bake at 350 degrees for 30 minutes.
Please feel free to change this recipe to suit your familie's tastes. Personally I like Charlotte's idea with the celery and onions and now saute the onions in butter, along with about an equal amount of chopped celery until tender. That way you never have to worry about the onions getting done enough.
As for the pasta, we personally prefer egg noodles over macaroni in this. Sometimes I just use whatever I have, sometimes a mix of several different pastas.
If you don't like cooking with the cream of mushroom soup, of course you can substitute cream of chicken or celery soup, and if you don't want soup in it at all, you can substitute sour cream or cream cheese and it's also good, but if you don't use the cream of soup I would suggest adding as much of the tuna water as possible to keep that great tuna flavor.
I prefer the tuna in water, and use as much of the tuna water as I can because I think it has a good flavor. Just use your own best judgement as to a good consistency, as this recipe is hard to mess up. Sometimes we don't always eat when I plan to and it stays in the oven a little longer than I'd like, so if yours seems too dry to you just add a little milk. You also can omit the bread crumbs/butter on top if you prefer, I usually do.
And I almost always double the tuna (or even add more), just because tuna is good for you and we love tuna casserole.