Funeral Potatoes

1 2lb frozen hash brown potatoes, thawed
1 onion, finely chopped (optional)
1 cube butter ( ½ C)
1½ -2 C sour cream
2 cans cream of chicken soup
2 C cheese, grated
1 ½ C crushed cornflakes
¼ C melted butter

Mix everything but the cornflakes and ¼ C butter. Pour into 9x13 dish and combine cornflakes and ¼ C butter. Sprinkle the cornflake mixture over the potato mixture and bake at 350 degrees for 45 minutes.