Heat oven to 350°F. Spray 2 quart casserole dish with nonstick cooking spray*. In large bowl stir sour cream and soup until well blended. Add Simply Potatoes, cheese and onion; mix well. Spoon mixture into dish. Cover; bake 45 minutes.
In small bowl, combine corn flakes or croutons with butter. Sprinkle over Simply Potatoes. Continue baking, uncovered, 20 to 25 minutes or until bubbly and golden brown. Sprinkle with parsley.