Preheat the oven to 350 degrees Fahrenheit
Bring a large pot of water to a boil, cook the ziti al dente according to package directions. Drain, rinse under cold water, and set aside.
In a large bowl combine the olive oil, garlic powder, zucchini, ricotta, half of the mozzarella, parsley, spinach, and mushrooms. Mix together well so all the vegetables and cheese have combined.
In a deep 13x9 inch baking dish, layer 1 cup tomato sauce, half of the pasta, half of the cheese/vegetable mixture. Repeat again with another layer of sauce, pasta, and cheese. Sauce one more time for the final layer, and sprinkle the remaining mozzarella on top.
Bake for 30 minutes covered, and an additional 20 minutes uncovered until pasta and cheese becomes hot and bubbly.
***If making ahead of time, follow steps 1-4, then wrap the baking dish in tin foil and refrigerate for up to 2 days. When ready to bake, follow step 5.