Place potatoes in an 8-inch square baking dish.  Sprinkle with cheese, ham and onions.  Beat eggs, milk, pepper, and salt; pour over all.  Cover and refrigerate for several hours or overnight.

Remove from refrigerator 30 minutes before baking.  Bake, uncovered at 350 degrees for 55-60 minutes or until a knife inserted near the center comes out clean.  Yield: 6 servings.