I love this casserole.  It is so versatile.  You can make it with almost anything.  This is a great way to use your leftovers.  This is taken from the CDKitchen.

Ingredients:

8 ounces sour cream
1 cup milk
1 cup water
1 teaspoon salt
1 teaspoon pepper

Choose a Sauce:

10 3/4 ounces cream of mushroom soup, condensed — undiluted
10 3/4 ounces cream of celery soup, condensed — undiluted
10 3/4 ounces cream of chicken soup, condensed — undiluted
10 3/4 ounces cheddar cheese soup — undiluted
29 ounces diced tomatoes with basil, garlic and oregano — undrained

Choose a vegetable:

14 1/2 ounces cut green Italian beans — drained
15 1/4 ounces sweet peas — drained
10 1/2 ounces asparagus cuts and tips — drained
15 1/4 ounces whole kernel corn — drained
13 1/2 ounces chopped spinach

Choose a starch:

2 cups uncooked elbow macaroni
1 cup uncooked regular rice
4 cups uncooked wide egg noodles
3 cups uncooked small pasta shells

Or… cover with mashed potatoes, hasbrowns, biscuits or a pie crust for a meat pie variation.

Add a Meat or protein source:

12 ounces solid white tuna in spring water — drained and flaked
2 cups chopped cooked chicken
2 cups chopped cooked ham
2 cups chopped cooked turkey
1 pound ground beef — browned and drained

Extras:

3 ounces canned mushroom slices — drained
1/4 cup sliced black olives
1/4 cup chopped red bell pepper — or green
1/4 cup chopped onion or scallions
1/4 cup chopped celery
2 cloves garlic — minced
4 1/2 ounces chopped green chiles
1 1/4 ounce taco seasoning mix

Top it off:

1/2 cup shredded mozzarella cheese
1/2 cup grated Parmesan cheese
1/2 cup shredded Swiss cheese
1/2 cup fine dry breadcrumbs
1 cup round buttery crackers — crushed
1 cup herb-seasoned stuffing mix