Thaw the frozen hash browns in the fridge overnight or in the oven at 200°F for about 20 minutes.
Preheat the oven to 350°F.
In a large mixing bowl, combine the sour cream, cream of chicken soup, 6 tablespoons of melted butter, salt, pepper, and dried onion. Mix until well combined.
Add the thawed hash browns and shredded cheddar cheese to the mixture. Stir gently until everything is evenly coated. Spoon the mixture into a 9x13'' baking pan.
For the topping, place the corn flakes in a large ziplock bag and gently crush them with your hands or a rolling pin until they are in small pieces.
Add the remaining 4 tablespoons of melted butter to the crushed cornflakes, mixing well. Sprinkle the mixture evenly over the potato mixture in the baking pan.
Bake the casserole uncovered at 350°F for 40-50 minutes, or until the top is golden and crispy. For an extra crispy topping, consider broiling for the last few minutes of baking.
Remove from the oven and let it cool slightly before serving. This dish pairs wonderfully with baked ham or your favorite main course.
Notes
For a crispy topping, consider broiling the casserole for the last few minutes of baking.