Brown and crumble the sausage in a large skillet or dutch oven over medium high heat and add the onions and garlic, cooking until tender. Stir in the mushrooms and cook until softened.
Add in the sauce, tomatoes and Italian seasoning. Bring to a gentle boil, reduce heat and simmer for 10 minutes, stirring occasionally. If your pan is big enough add the pasta to the sauce and stir to coat. If needed, transfer sauce and pasta to a larger bowl to stir together.
For the Cheese mixture:
Combine the ricotta, parmesan, eggs, parsley, salt and pepper in a small dish.
Assemble the Baked Ziti:
Lightly coat a 9x13" casserole dish with non-stick spray. Layer half of the pasta mixture on the bottom of the casserole dish. Top with the cheese mixture and spread to an even layer. Sprinkle half of the shredded mozzarella cheese on top. Spread the remaining noodles and sauce over that, followed by the remaining mozzarella cheese.
If baking right away:
Cover with foil and bake in a preheated 350 degree oven for 25 minutes, then remove foil and continue baking for an additional 15 to 20 minutes, or until center is bubbly. Enjoy!
If freezing for later:
Let cool to room temperature then cover with an airtight lid. If no lid is available, cover with plastic wrap and then a double layer of tin foil. Freeze.
To Bake From Frozen:
Take casserole out of freezer and remove lid or any plastic wrap. Cover with foil and let it sit on the counter while the oven is preheating. Bake in 350 degree oven for 1 hour, remove foil and continue baking for an additional 10 to 15 minutes, or until center is bubbly. Enjoy!