Bring a large pot of water to a boil. Cook ziti in boiling water for 8 minutes, until al dente. Drain and rinse ziti with cold water to stop cooking further. Set aside.
While water is boiling and ziti is cooking, saute mushrooms and spinach in olive oil. Set aside.
In a large bowl, mix ricotta cheese and half of the jar of Barilla Traditional sauce. Add cooked ziti, sauteed mushrooms and spinach. Stir.
Add salt, pepper and oregano to taste.
Shred 4 oz Galbani mozzarella cheese into pasta. Stir gently.
Spread half of remaining pasta sauce into the bottom of a baking dish. Pour ziti mixture into the dish.
Cut 4 oz of Galbani mozzarella cheese into thin slices and place on top of pasta. Pour remaining pasta sauce on top.
Bake for 25-30 minutes, or until cheese is bubbly and lightly browned.