Add the frozen hash browns and ham and cheese to a large bowl. Toss to combine. Pour mixture into a 9x13 inch dish that you have sprayed with the cooking spray.
In a large bowl (can use that same bowl) whisk together eggs with milk and salt and pepper
Pour the egg mixture over the hash browns mixture. Pat everything down with a spoon.
Bake for one hour and twenty minutes uncovered.
Notes
Optional: Add minced parsley to the top of the casserole.
*You can assemble this the night before. Assemble according to the directions. But don't bake and cover with plastic wrap and refrigerate overnight. Remove plastic wrap and bake.