1Brown ground beef & onion, drain fat. Season with salt and pepper to taste.
Slice potatoes very thin (I use a mandolin).
Mix soup, sour cream and milk.
In a 13x9 casserole, place a layer of potato. Top with a layer of ground beef and onion. Add 1/2 cup veggie, if desired. Pour on half the sauce and top with 1 cup of the cheddar cheese. Repeat with another layer.
Cover with foil and bake at 350 for 1 hour. Remove foil and bake another 10 minutes, or until cheese is golden brown.