Preheat the oven to 400 degrees F (200 degrees C).
Beat eggs and milk together in a shallow bowl. Stir bread crumbs and Parmesan cheese together in another shallow bowl. Dip meatloaf slices, one at a time, into the egg mixture and bread crumb mixture to coat all sides.
Heat oil in a large oven-safe skillet over medium-high heat. Cook the coated meatloaf slices until browned, turning once halfway, about 5 minutes. Drain off oil.
Pour spaghetti sauce evenly over the browned meatloaf slices. Sprinkle with mozzarella cheese.
Bake in the preheated oven until sauce is heated through and cheese is melted, 8 to 10 minutes.
