Cook Potatoes In Water Until Almost Tender; Drain. In A Mixing Bowl, Bet Eggs; Gradually Add Cheese Spread And Milk (Mixture Will Appear Lumpy). Stir In Potatoes, Ham And Half The Onions. In A 10-In. Ovenproof Skillet, Melt Butter Over Low Heat; Remove From The Heat. Pour Egg Mixture Into Skillet. Bake, Uncovered, At 350 Degrees F For 20 Minutes. Sprinkle With Remaining Onions; Bake 5-10 Minutes Longer Or Until A Knife Inserted Near The Center Comes Out Clean. Let Stand For 5 Minutes Before Cutting.