- 2 (10.75 ounce) cans cream of mushroom soup, divided
- 1 cup cooked ham slices, or to taste, divided (optional)
- 6 large russet potatoes, or more to taste, thinly sliced and divided
- 1 onion, thinly sliced and divided
- 1 1/2 cups shredded Italian cheese blend, or more to taste, divided
- 1/3 cup milk
- Preheat oven to 350 degrees F (175 degrees C).
- Spread about 2/3 of one can of mushroom soup into the bottom of a 9-inch square baking dish. Layer about half the ham slices, 1/3 of the potato slices, half the onion slices, and 1/3 of the Italian cheese blend, respectfully, atop the mushroom soup.
- Layer about half the remaining potatoes atop the first layers. Mix soup remaining in first can with milk; pour over the potatoes.
- Finish layering with remaining ham slices, remaining onion slices, about half the remaining cheese, and the remaining potato slices. Spread second can of mushroom soup over the top layer. Sprinkle remaining cheese over the soup. Cover dish with aluminum foil.
- Bake in preheated oven for 1 hour. Remove foil and continue baking another 45 minutes. Turn heat off, replace aluminum foil on the dish, and let the potatoes bake in the cooling oven until the sauce is absorbed, about 30 minutes more.