Preheat the oven to 350°F. Lightly grease a 9x13-inch baking dish with nonstick cooking spray.
In a large mixing bowl, whisk together the sour cream, cream of mushroom soup, and ¼ cup (half) of the melted butter until smooth.
Stir in the frozen hash browns, diced ham, shredded cheddar cheese, salt, and black pepper until everything is evenly coated.
Spread the mixture evenly into the prepared baking dish.
Lightly crush the corn flakes and sprinkle them evenly over the top of the casserole.
Drizzle the remaining ¼ cup melted butter evenly over the corn flakes.
Bake uncovered for 45-50 minutes, or until the casserole is hot and bubbly and the topping is golden brown.
Let the casserole rest for 10 minutes before serving.
Notes
Refrigerate the leftovers in an airtight container for up to 5 days. You can use diced hash browns instead of shredded for this recipe if you prefer. There is no need to thaw the hash browns before mixing them into the casserole.For an extra crispy topping, broil the casserole for 1-2 minutes at the end of the baking time, watching closely to prevent burning.Freshly shredded cheddar cheese melts more smoothly than pre-shredded cheese and gives the casserole the best texture.