1. Preheat oven to 350º F. 2. In a large bowl, stir cream of chicken soup and sour cream into mashed potatoes. 3. Mix in cheddar cheese, then season generously with salt and pepper. 4. In a separate bowl, toss corn flakes with melted butter until they’re all evenly coated. 5. Transfer potatoes to a 9×13-inch baking dish and cover with corn flakes. 6. Place baking dish in oven and bake for 45 minutes, or until corn flakes are golden brown. 7. Remove from oven and serve hot.