Stir together first 6 ingredients in a large bowl.
Spoon potato mixture into a lightly greased 13- x 9-inch baking dish. Sprinkle evenly with crushed cornflakes, and drizzle evenly with butter.
Bake at 325° for 1 hour and 20 minutes or until bubbly.
Note: For testing purposes only, we used Ore-Ida Southern Style Hash Browns.