Golden Scalloped Potatoes

1 can cream of celery soup
1/3 cup milk
dash pepper
4 cups thinly sliced potatoes
1 small onion, thinly sliced
1 cup shredded sharp Cheddar cheese
1 Tbsp. butter
paprika

Combine soup, milk, and pepper. In buttered 1 1/2-quart casserole, arrange alternate layers of potatoes, onion, soup mixture, and cheese. Dot top with butter; sprinkle with paprika. Cover; bake at 375 degrees for 1 hour. Uncover; bake 15 minutes more or until potatoes are done.