In a skillet sautee1lb ground beef and 1cup onion,drain off fat.stir in 1 8oz can of tomato sauce. 1/2 tsp salt1/4 tsp black pepper. 1/2 tsp celery salt,or season salt.Spoon into shallow 1 1/2 qt baking dish.spread 3 cups mashed potatoes smoothly on top of ground beef mixture. Top with 1 cup shredded cheddar cheese.
Bake 30-35 min uncovered until cheese is melted and casserole is bubbly.
optional.... you can add vegetables before topping with mashed potatoes , I use corn and mushrooms . But you can use green beans, peas, mixed vegetables, (don't forget to drain them.)