Preheat oven to 375.
Spray a 9x12 baking dish with non-stick cooking spray.
Cook the noodles 2 minutes LESS than the package directions. Do not throw away the plastic package inserts; you will need these later.
Once the noodles are cooked and cool enough to handle, transfer each into a spot in the original plastic insert until ready to fill.
Brown the sausage in a large skillet. When cooked transfer it to a large plate covered with a paper towel to soak up an excess oil.
Place the extra virgin olive oil into the same skillet, add the spinach, and cook until wilted.
Remove the spinach and allow it to cool. When it is cool enough to handle, squeeze out any excess liquid.
Rough-chop the spinach and add it to a large mixing bowl.
In the same bowl with the spinach, add the sausage, ricotta cheese, parmesan cheese, ½ of the mozzarella cheese, and seasonings. Mix with a large spoon until fully combined.
Pour ¾ of the jar of pasta sauce into the bottom of the prepared baking dish.
Fill each cannelloni noodle with the ricotta sausage mixture.
Lay the filled noodles side-by-side on top of the sauce.
Spoon the remaining sauce over the filled noodles.
Cover the dish with foil and bake for 40 minutes.
After 40 minutes, remove the foil, top with remaining mozzarella cheese, and cook for another 5-7 minutes.
Allow the dish to rest for 15 minutes, before serving.