Scalloped Potatoes
["3 Tbsp. butter", "2 Tbsp. flour", "1 1/2 tsp. salt", "1/8 tsp. pepper", "3 c. milk", "1/2 c. American cheese", "6 medium potatoes, thinly sliced", "2 Tbsp. chopped onion"]
["Make sauce of first 5 ingredients.", "Add cheese.", "Place half of potatoes in a greased casserole (2-quart).", "Cover with half the onion and half the sauce.", "Repeat layers.", "Bake for 1 hour at 350\u00b0.", "Uncover and bake 1/2 hour more."]
["butter", "flour", "salt", "pepper", "milk", "American cheese", "potatoes", "onion"]