Heat oven to 350°F. Spray 8-inch square (2-quart) glass baking dish with cooking spray.
In large bowl, mix potatoes, ham and 1 1/2 cups of the cheese. Spread in baking dish. In same bowl, mix sour cream, milk and seasoned salt with wire whisk until well blended. Spoon over potato mixture; stir to mix. Cover baking dish with foil.
Bake 45 minutes. Sprinkle with remaining 1/2 cup cheese. Bake uncovered about 10 minutes longer or until bubbly and thoroughly heated.