Preheat oven to 350°. In a large bowl, combine potatoes, soup, sour cream, 1-3/4 cups cheddar cheese and Parmesan cheese. Transfer to a greased 3-qt. baking dish. Sprinkle with remaining cheddar cheese.
Bake, uncovered, 40-45 minutes or until bubbly and cheese is melted. Let stand 5 minutes before serving. Yield: 10 servings.