Pre-heat the oven to 350F and get a large pot of water on the stove so it can start to boil. This will take at least 10-15 minutes.
While the pasta is coming to a boil, chop the onion, cut up the broccoli, slice the mushrooms and mince the garlic. Heat a large sauté pan to medium heat with some olive oil. Throw in the broccoli, mushrooms and half of the onion. Season with some salt and sauté for about 5-7 minutes and then turn off the heat and set aside.
The water should be boiling about now, so salt the water and throw in the pasta. Cook according to the package but it should take 5-7 minutes for al dente.
While the veggies are sautéing and the pasta is cooking, quickly make the marinara sauce by sautéing the onion for 3-4 minutes. Then add in the garlic for a minute, followed with the tomatoes, basil, oregano and a large pinch of kosher salt. Let simmer while everything else is coming together.
Ok, so, now that everything made. the veggies sautéed, the spinach thawed, the marinara sauce made, it's time to assemble.
In a large bowl, mix the pasta, veggies, ricotta cheese and marinara sauce. Taste and adjust the seasonings. Place in a 9x13 baking pan and cover with the shredded mozzarella cheese. Cover with aluminum foil and place in the oven for 30 minutes. After 30 minutes, take the aluminum foil off and cook for another 10-15 minutes.
Serve and enjoy!