Creamy Scalloped Yukon Spuds

10 c Thinly sliced Yukon potatoes

1 cn Cream of mushroom soup

-10-1/2 ounce can 1/4 c Finely chopped onion

1 c Milk

1 Stick butter or margarine

-melted 2 c Grated cheddar cheese

1/2 ts Salt

1/2 ts Pepper

Spread half of the sliced potatoes in the bottom of a greased baking dish. In a medium bowl, combine remaining ingredients (except potatoes) and pour half the mixture over the first layer of potatoes. Repeat layers of potatoes and mixture. Cover and bake at 350 degrees for 1 hour. Uncover and bake 30 to 45 minutes longer.