Buttery Onion Soup
["2 c. thinly sliced onions", "1/4 c. flour", "2 c. milk", "salt and pepper to taste", "1/2 c. butter or margarine", "2 c. chicken broth", "1 1/2 to 2 c. Mozzarella cheese", "croutons (optional)"]
["In a large kettle, saute onions in butter over low heat until tender and transparent, about 20 to 30 minutes.", "Blend in flour. Gradually add broth and milk; cook and stir over medium heat until bubbly.", "Cook and stir 1 minute more; reduce heat to low.", "Add cheese and stir constantly until melted.", "Do not boil.", "Season to taste.", "Serve with croutons."]
["onions", "flour", "milk", "salt", "butter", "chicken broth", "Mozzarella cheese", "croutons"]