1Heat oven to 400°F. Spray 9-inch glass pie plate with cooking spray. Layer chicken, ham and cheese in pie plate.
2In medium bowl, mix remaining ingredients with whisk or fork until blended. Pour over cheese in pie plate.
3Bake 30 to 35 minutes or until knife inserted in center comes out clean. Let stand 5 minutes before serving. If desired, serve with additional potato topper and fresh chives.