Combine the eggs, ricotta, parsley, salt, pepper and half of the mozzarella and Parmesan cheeses.
Stuff mixture into shells (I used a cookie press, but you can also put the stuffing into a plastic bag, cut a corner off, and squeeze). Place shells into a 9x13 baking dish that has been sprayed with non-stick spray.
In a large bowl, combine the pasta sauce, mushrooms, remaining cheese and sausage. Pour over the pasta shells.