Remove hash browns from the freezer and set them aside to thaw slightly while you prepare the casserole.
Preheat the oven to 350℉. Grease your 9x13" baking pan with butter or cooking spray such as Pam.
In the microwave, melt 1 stick (½ c) of butter in a heat safe bowl.
In a large mixing bowl, stir together sour cream, cheese, melted butter, seasonings, and cream of chicken soup until fully combined. It doesn't need to be perfectly smooth.
Spread slightly thawed hash browns in your prepared pan, breaking up any large frozen chunks if needed.
Using a rubber spatula or wooden spoon, spread the soup and cheese mixture as evenly as possible over the top of the potatoes.
Sprinkle corn flakes on top of sour cream, cheese and soup mixture in an even layer.
Melt the additional 1/2 stick (1/4 c) of butter in the microwave, and drizzle over the tops of the cornflakes.
Bake for 1 hour. Serve soon-ish as the cornflakes don't chill and re-heat well (thought the rest of it does!).