preheat oven to 350' F - bake for about an hour
Slice the zucchini lengthwise, scoop out the filling onto a chopping board, rough chop the filling and place in a large bowl.
brown sausage and drain the excess fat off. saute the onions until they are soft. set aside till they cool a bit, 5 minutes is fine. add these to the zucchini in the bowl.
dice or shred up some mozzarella and add it to the bowl with the onions, sausage and zucchini
Add the rice and Parmesan cheese and season to taste with salt and pepper
place the zucchini boats into a large baking dish. Fill each boat with the stuffing you just made.
cover each boat with marinara sauce and the shredded cheese. cover your dish with tinfoil and bake for 30-40 minutes. You may need to remove some of the excess liquid. Remove the foil and bake for another 20 minutes or until browned.