Heat oven 350. Cook potatoes in boiling water in covered large saucepan 10 to 12 min. or just until potatoes are tender; drain. Place 3/4 of potatoes in large bowl. Add sour cream; mash intil smooth. Stir in belbeeta, ham and onions. Add remaining potaotes; mix lightly.
Spoon into 13x9 in baking dish sprayed with cooking spray; sprinkle with Parmesan cheese
Bake 30 min, or until heated through
