Onion and Cheese Soup

1 large onion, chopped
3 tablespoons butter
3 tablespoons all purpose flour
1/2 teaspoon salt
Pepper to taste
4 cups milk
2 cups (8 ounces) shredded Colby-Jack cheese
Seasoned Croutons
Grated Parmesan Cheese, optional

1. In a large saucepan, saute the onion in butter. Stir in the flour, salt, and pepper until blended. Gradually add milk, and bring to a boil, cook and stir for 2 minutes or until thickened. 

2. Stir in the cheese until melted. Serve with croutons and Parmesan cheese if desired.