I can't believe no one has rated/reviewed this recipe. I've been making it for years from the dogged-earred pages of the battle worn paperback book. You can use leftover mashed potatoes - warm them and add a little half and half and whatever else suits your taste (I like to add some sauteed minced onion and some garlic powder). You can mix the type of potato (mashed red potatoes in their skins, I throw in a sweet potato if I have one). If you boil the potatoes add an onion cut into four pieces and either remove the onion or mash it with the potatoes - don't be afraid of seasoning the otherwise bland potato mixture. I also add a little Worchestershire sauce to the meat mix so it tastes more like steak and not a meatball. I spread barbeque sauce or catsup on the top and then drape some bacon strips on top. Comes out moist and delicious. A hearty one pot meal with leftovers.
Great dish, does take quite a while if makes potatoes from scratch. Turned out very good. Added parmesan cheese over the potatoes and extra onion.