Prepare the Potatoes. Peel the potatoes and dice them into small pieces. Place the potatoes in a large bowl of cold water to prevent them from turning brown.
Layer the Casserole. In a mixing bowl, combine the sour cream, milk, melted butter, garlic powder, onion powder, dried thyme, salt, and pepper. Mix well until all the ingredients are evenly incorporated. Add the diced potatoes, diced ham, and shredded cheddar cheese to the bowl. Gently toss everything together until the potatoes and ham are coated with the creamy mixture.
Air Fry the Casserole. Preheat your air fryer to 375F. Transfer the potato mixture into a greased baking dish that fits inside the air fryer basket. Spread it out evenly. Place the baking dish in the preheated air fryer and cook for about 20-25 minutes, or until the potatoes are golden brown and crispy on top.
Garnish and Serve. Once the casserole is cooked, remove it from the air fryer and let it cool for a few minutes. Sprinkle chopped fresh parsley on top for a vibrant touch of color and freshness.