Position an oven rack in the top third of the oven and preheat to 400 degrees F. Coat a 9-by-13-inch baking dish with cooking spray.
Lay a chicken breast on a cutting board with the tapered end pointing at you. Using a sharp knife held horizontally to your work surface, begin slicing the chicken breast in half, starting at the thicker end of the breast and slowly working towards you, leaving an outer edge connected so you can open it like a book. Butterfly all the breasts in this manner and set in the fridge until ready to roll.
Cut six 1/4-inch-thick slices from the mozzarella, then finely chop the rest.
To build the pizza rolls: Open the butterflied chicken breasts so they lay flat on your cutting board. Sprinkle the chicken evenly with salt and pepper. Top with some spinach leaves, sausage, sun-dried tomatoes and chopped mozzarella. Roll the chicken around the filling and tuck into itself so that the seam is facing down. Place the rolled chicken in the prepared baking dish, seam-side down. Sprinkle with salt and pepper. Repeat with the remaining chicken and fillings.
Bake the chicken until the internal temperature reaches 165 degrees F, 20 to 25 minutes. Meanwhile, heat up the pizza sauce. About 3 minutes before the chicken is done, top each piece with a slice of mozzarella.
Spoon the warm pizza sauce over the chicken and garnish with the Parmesan and basil.