Grease a 9 by 13-inch pan. Layer the frozen potatoes in the pan. Sprinkle the ham, cheese, and onions over the potatoes. In a medium bowl (I use my blender), combine the eggs, milk, salt, and pepper. Pour the egg mixture over the potato mixture. Cover and refrigerate overnight.

In the morning, preheat the oven to 350 degrees. Bake the casserole uncovered for 55-60 minutes or until the eggs are set.