Use a 6-quart slow cooker sprayed with cooking spray. Pour the entire bag of frozen country potatoes into the insert. In a large mixing bowl, whisk together the eggs, milk, salt, and pepper. Stir in cheese and ham. Pour this mixture evenly over the top of the potatoes.
Cover and cook on low for 6-8 hours, or on high for about 4 hours. Your casserole is finished when the top has begun to brown and pull away from the sides and the egg is fully cooked.