Fry about 2 lbs. of hamburger with 1 chopped onion. Place in baking dish. Make or use leftover mashed potatoes and place them on top of the hamburger. Bake for hour at 350 degrees, just until warmed through. Serve with gravy.
Some people put corn or peas, whatever between the hamburger and the potatoes.
In an effort to cut down on fat, I've tried using turkey-burger instead of hamburger, we didn't care for it. It so drastically changed the taste. Some people use instant mashed potatoes for a quick dinner. In our house we like garlic, so while I'm boiling the potatoes for mashing, I throw a clove or two of garlic in the water. Tailor it to your taste and let me know how it comes out.