In large mixing bowl, combine soup, sour cream and milk; salt and pepper to taste. Stir in hash browns, cheese and onions; mix until well combined.
Transfer to a grease 2½-quart baking dish. Combine crushed corn flakes and melted butter; sprinkle over potatoes.
Bake, covered, in a preheated 350°F oven 45 minutes. Remove cover and continue baking 15 minutes or until bubbly.