Combine potatoes, 1/2 cup butter, onion, soup, sour cream and cheese. Stir well.
Spoon mixture into a buttered ovenproof 2 1/2 quart casserole.
Place corn flakes into a small Ziploc bag and crush them until fine using a rolling pin or the back of a large spoon. Stir in the remaining butter and corn flakes. Sprinkle over potato mixture.
Bake in a pre-heated 350°F oven for 50 minutes.
This recipe was given to me by my dear grandmother, and whenever I prepare it, it brings back fond memories.