01 -
Preheat oven to 350°F. Brown ground beef in large skillet over medium-high heat, breaking up with wooden spoon. Drain grease completely and season with salt and pepper.
02 -
In greased 9x13 baking dish, layer half the sliced potatoes, overlapping slightly. Sprinkle half the onion soup mix over potatoes, then add half the sliced onions.
03 -
Spread browned ground beef over potato layer. Add remaining potatoes, onion soup mix, and onions. Pat down gently to compress layers.
04 -
Spread cream of mushroom soup evenly over top layer using back of spoon. Add splash of milk if soup seems too thick.
05 -
Cover with foil and bake 45 minutes. Remove foil, top with shredded cheese, and bake uncovered 15-20 minutes until cheese is bubbly and potatoes are fork-tender.
06 -
Let casserole rest 10 minutes before serving to allow layers to set. Cut into squares and serve hot.