Begin by peeling and cubing about three cups of potatoes. Place them in a pot of salted water and bring to a rolling boil. Cook for 15-20 minutes until fork-tender. Drain and mash with milk, butter, salt, and pepper.

In a skillet, heat olive oil and sauté onion and garlic for 3-4 minutes. Add ground beef and cook until browned, about 5-7 minutes.

Stir in mixed vegetables, cream of mushroom soup, and Italian seasoning. Simmer for 5-7 minutes until thickened.

In a baking dish, spread half of the mashed potatoes, layer the meat mixture, sprinkle with cheese, and dollop remaining potatoes on top.

Bake at 375°F (190°C) for 25-30 minutes until golden and bubbly. Let rest for 5-10 minutes before serving.