Cheesy Onion Soup

This soup is absolutely perfect for this colder, rainy weather.  It's sweet, creamy and simply delicious!  Enjoy!
-3 Tbs butter
-1 large onion, finely chopped
-3 Tbs flour
-4 cups milk
-2 tsp salt
-1 tsp pepper
-2 cups Colby-Monterey Jack cheese, shredded
-seasoned salad croutons
-grated parmesan cheese
Melt the butter in a large saucepan.  Add the onion and cook until translucent.  Sprinkle the flour and give it a good stir.  Gradually,  add the milk.  Season with the salty and pepper.  Bring to a boil.  Cook for about 5 minutes, or until thickened.
Remove the pot from stove and stir in the cheese until melted.
Ladle into bowl and top with croutons and cheese.  Enjoy!