Plenty of cheese and cream of celery soup, along with a little sour cream, make this tasty hash brown casserole. This recipe calls for a package of refrigerated hash browns, but thawed frozen hash browns can be used as well. This casserole makes a wonderful brunch dish, and it's a perfect side dish for just about any meal, plain or fancy. It's also a great casserole to take along to a potluck dinner.