Scalloped Potatoes
["1/2 c. chopped onion", "2 Tbsp. margarine or butter", "2 Tbsp. all-purpose flour", "1 1/4 c. milk", "3 medium potatoes, peeled and thinly sliced", "1/2 tsp. salt", "1/8 tsp. pepper"]
["For sauce, cook onion in margarine until tender.", "Stir in flour, salt and pepper.", "Add milk all at once.", "Cook and stir on medium heat until thick and bubbly.", "Remove from heat.", "Place half the sliced potatoes in a greased casserole.", "Cover with half the sauce.", "Repeat layers.", "Bake, covered, in a 350\u00b0 oven for 35 minutes.", "Uncover; bake 30 minutes more or until potatoes are tender."]
["onion", "margarine", "flour", "milk", "potatoes", "salt", "pepper"]