Preheat oven to 350 degrees. Spray a 9x6-inch or 9x9-inch baking dish with baking spray, set aside.
In a large skillet set over medium heat, add olive oil. When the oil is hot, add mushrooms and cook for 3-4 minutes, then add the onions and cook until translucent. Add garlic and cook until fragrant, about 1-2 minutes.
Remove from the stovetop and allow to cool for 5 minutes, then combine with the Italian seasoning, garlic powder, salt, pepper, spinach, cream cheese, ricotta, 1 cup of mozzarella, 3 tablespoons of parmesan, and the chicken. Mix until combined.
Spread 1/4 of pasta sauce in the bottom of the prepared baking dish. Cover with a layer of noodles, 1/4 of the sauce, then half of the filling. Top with another layer of noodles, 1/4 of the sauce then the remaining chicken mixture. Add a final layer of noodles and sauce, then sprinkle the remaining mozzarella and parmesan over top.
Cover with foil and place in the oven to bake for 30 minutes. Remove the foil and bake uncovered for an additional 15 minutes. Remove from the oven and allow to rest for 10 minutes before cutting and serving. Garnish with freshly chopped parsley, if desired.