Preheat oven to 350 degrees.Add the frozen potatoes, ham, and cheese to a large bowl. Toss to combine. Pour the mixture into a 9 x 13 baking dish that has been sprayed with cooking spray.In a large bowl, whisk the eggs with the milk, salt, and pepper (I use the same bowl from step 1).Pour the egg mixture over the hash brown mixture. Pat everything down with the back of a wooden spoon.Bake for one hour. The center should be set and the edges should be golden brown.