Another favourite from Betty Crocker. I usually make these when serving ham.
UPDATE 2022 - add another vegetable like cauliflower or broccolini.
medium boiling or baking potatoes (2 lb)
cup butter or margarine
medium onion, chopped (1/2 cup)
tablespoon all-purpose flour - gluten free or corn starch
cups shredded natural sharp Cheddar cheese (8 oz)
cup dry bread crumbs (any flavor) I never add the bread crumbs
Heat oven to 375ºF.
Scrub potatoes but do not peel. Cut into 1/8-inch slices to measure about 4 cups.
Melt butter in 2-quart saucepan over medium heat. Cook onion in butter about 2 minutes, stirring occasionally, until tender. Stir in flour, salt and pepper. Cook, stirring constantly, until bubbly; remove from heat.
Stir in milk and 1 1/2 cups of the cheese. Heat to boiling, stirring constantly. Boil and stir 1 minute.
Spread potatoes in ungreased 1 1/2-quart casserole. Pour cheese sauce over potatoes.
Bake uncovered 1 hour. Mix remaining cheese and the bread crumbs; sprinkle over potatoes. Sprinkle with paprika. Bake uncovered 15 to 20 minutes longer or until top is brown and bubbly.