Heat the butter in a 12-inch skillet over medium heat
Add the celery and cook for 5 minutes or until tender-crisp
Stir in the soup, water anduncooked pasta and heat to a boil
Reduce the heat to low
Cover and cook for 10 minutes or until the pasta is tender, stirring occasionally
Stir in the tuna and ⅓ cupcheese and cook until the mixture is hot
Season with salt and pepper
Sprinkle with the croutons and the remaining ⅓ cup cheese (the heat from the pasta mixture will melt the cheese)
