To make this quick meal even quicker, use instant mashed potatoes. You can make it "pretty" by squeezing potato mixture through pasty bag with a large star tip.
- Cook potatoes in boiling salted water until tender, about 20 minutes; drain.
- Meanwhile, in large frying pan, cook ground beef and onion until meat is lightly browned and onion is tender; drain off fat.
- Stir in green beans, tomato soup, water, salt and pepper.
- Turn mixture into a 1 1/2 quart casserole.
- Mash potatoes while hot; blend in egg.
- Add enough milk to make potatoes fluffy.
- Season potatoes to taste with salt and pepper.
- Spread or drop potato mixture on top of meat mixture.
- Sprinkle with cheese.
- Bake, uncovered, at 350 degrees for 20 to 25 minutes until cheese is melted and sauce is bubbly.