Preheat the oven to 375F
Add the sausage to an oven safe pot and cook. Break up the large peices of sausage so that they are crumbled and let them start to brown
Add garlic and onion, and cook.
Add Pepperoni (or prosciutto or pancetta). Let this cook together until sausage is nice and brown. It is ok if it is not completely cooked as it will cook later on too
Add the crushed tomatoes, oregano, and spinach and mix it up
Add the marinara sauce and parmesan, and mix
Add the penne and the water, and then make sure all of the penne is pushed underneath the water mixture before you put it in the oven.
Cover and Bake this for 40 minutes
Use oven safe mitt to remove from oven as the pot will be very hot!
Slowly uncover the pot and add mozzarella cheese. Add some first and mix it in. Then add a nice layer on top.
You can bake covered for 5 more minutes, or you can put under a broiler for 4 or 5 minutes so that the mozzarella cheese gets nice and brown. Enjoy!