Preheat oven to 425 degrees F. Spray a 9 x 13-inch baking dish with cooking spray.
In a large bowl, whisk together chicken broth, Alfredo sauce, garlic and salt until completely combined.
In the prepared baking dish, stir together raw chicken, spinach, ¼ cup of chopped basil leaves, tomatoes, and uncooked pasta. I like to use my hands to gently combine and evenly distribute all of the ingredients. Pour chicken broth mixture over top and stir to combine.
Cover the dish tightly with foil and bake for 40 minutes.
Uncover; stir. At this point you should check the pasta to make sure that it is al dente (firm but just about finished cooking). If it’s still too hard, cover the dish and return to the oven until pasta is al dente. Then move on to the next step.
Sprinkle mozzarella and Parmesan cheeses over the top. Bake uncovered for 5-10 more minutes (or until cheese is melted, pasta is tender, and chicken is cooked through).
Garnish with remaining basil leaves just before serving.