Preheat oven to 425°F. Spray a 13-inch by 9-inch baking dish with nonstick cooking spray.
In the prepared baking dish (or in a separate large bowl), stir together uncooked pasta, marinara sauce, water, salt, pepper, and raw chicken. Tips: See my suggestions below if you'd like to add even more flavor to the dish (like red wine, garlic powder, onion powder, Italian seasoning, or crushed red pepper flakes).
Transfer the mixture to the prepared baking dish. Cover tightly with aluminum foil. Make sure that your dish is covered tightly so that none of the moisture escapes (the pasta needs to absorb the liquid as it cooks). Bake the covered dish for 30 minutes.
Uncover and give the pasta a good stir. At this point the pasta will still be firm and there will still be quite a bit of liquid in the dish. That's fine!
Spread mozzarella over the top and sprinkle with breadcrumbs and Parmesan cheese. Bake uncovered for 10-15 more minutes (or until cheese is melted, top is golden brown, pasta is tender, and chicken is cooked through).
Garnish with fresh herbs, if desired. Serve!