Cheesy Ham Potato Casserole
["2 Tbsp. onion", "1/4 c. butter, melted", "1/4 c. all-purpose flour", "1 tsp. salt", "1/2 tsp. dry mustard", "1 1/2 c. milk", "2 c. shredded cheese, divided", "2 c. cooked ham", "6 c. cooked potatoes"]
["Saute onion in butter in a large saucepan until tender.", "Add flour and seasonings. Cook 1 minute, stirring constantly. Gradually add milk.", "Cook over medium heat, stirring constantly until thick.", "Add 1/2 cup cheese, stirring until cheese melts. Add ham and potatoes. Spoon into greased 2-quart shallow baking dish. Bake uncovered at 350\u00b0 for 25 minutes. Sprinkle with remaining cheese."]
["onion", "butter", "all-purpose", "salt", "dry mustard", "milk", "shredded cheese", "ham", "potatoes"]