Easy Cheesy Scalloped Potatoes

6 large or 9 small potatoes, cooked
1/4 cup butter
1 can cream of chicken soup
1 pint sour cream
1/2 cup chopped green onion
1 1/2 cups grated Cheddar cheese

Cook potatoes whole. Peel and cut into 1 to 1 1/2-inch chunks. Heat butter and soup together. Blend in other ingredients. Add to potatoes in large casserole dish. Bake at 350 degrees F for 45 to 60 minutes. This can be made ahead, and it also freezes well.