1Heat oven to 350°F. Spray shallow 1 1/2-quart casserole or gratin dish with nonstick cooking spray. In sprayed casserole, combine potatoes, cheese and onions; mix well.
2In medium bowl, combine all remaining ingredients; blend well. Pour over potato mixture; mix well.
3Bake at 350°F. for 45 to 50 minutes or until potatoes are tender and top is golden brown.