Preheat oven to 350 degrees. Butter a 2 qt casserole. Make a basic white sauce of butter, flour, salt, pepper & milk. Place half the potatoes in casserole. Cover with half the onion and half the sauce. Repeat layers. Cover and bake about an hour. (I like to cook it a bit longer, about 1 hour and 15 minutes before uncovering it.) Test to make sure potatoes are almost, but not quite, fork tender. Uncover and bake 30 minutes longer.

edition.

Left over cooked ham layered in the middle makes it almost a one dish meal, and is a good addition...tho I usually serve this with ham to begin with.