In a large kettle, saute onions in margarine over low heat until tender and transparent, about 20-30 minutes. Blend in flour. Gradually add broth and milk; cook and stir over medium heat until bubbly. Cook and stir for 1 minute more; reduce heat to low. Add mozzarella cheese and stir constantly until melted (do not boil). Season to taste with salt and pepper. Serve with croutons if desired.

of Sunburst, Montana.