1. Heat oven to 350 degrees F. Spray 12x8-inch (2 quart) glass baking dish with cooking spray. In 10-inch skillet cook ground beef over medium-high heat until thoroughly cooked; drain. Stir in mixed vegetables, gravy and salt. Cook 3-4 minutes or until vegetables are thawed and mixture is thoroughly heated.
2. In baking dish, layer 3 cups of the potatoes and 1 cup of the cheese. Spoon ground beef mixture over cheese. Top with remaining potatoes. Cover with foil.
3. Bake 55-60 minutes or unril bubbly. Remove foil. Sprinkle with remaining 1 cup cheese. Bake uncovered 5 minutes longer or until cheese is melted.