This can be mixed the day before and kept in the refrigerator, then quickly baked before the event.
2 lbs frozen hash brown potatoes, completely thawed
1/2 cup melted margarine
1 tsp salt
1/4 tsp pepper
1/2 cup chopped onion
1 can cream of chicken soup
1 pint sour cream
10 oz shredded cheddar cheese
Topping: 2 cups crushed croutons, seasoned bread crumbs
Mix all ingredients and pour into greased casserole dish. Top with croutons/bread crumbs and bake 45 minutes at 350.
This sounds like you could easily add chopped ham or ground beef, a little frozen brocolli, and maybe increase cheese for a 1 dish dinner!