Preheat oven to 375°F. Cook stuffing following package directions.
Add chicken breast, stirring to combine, and set aside.
Spray a 9x13 baking dish with a non-stick cooking spray. Stuff shells with the stuffing mixture and place in prepared dish, open and facing down.
Heat the soup, milk and water in a sauce pan, stirring until evenly combined. Pour over top of the stuffed shells.
Bake 35 minutes.
Take out of oven and sprinkle with Swiss cheese.
Bake an additional 5-10 minutes until cheese is melted.
Let sit 5 min before serving. Enjoy!