Step 1

Preheat the oven to 400ºF. Spray a 9x13 baking dish with cooking spray. Bring a large pot of water to a boil and salt it.

Step 2

Place olive oil in a large skillet over medium-high heat. When the oil is hot, add the mushrooms and cook, stirring occasionally, until they soften, release their water, and begin to dry out again, about 5 minutes. Add the onion and garlic, sprinkle with salt and pepper, and lower the heat to medium. Continue to cook, stirring occasionally, until the vegetables are soft, about 5 minutes.

Step 3

Add the tomatoes one at a time, crushing them with your hand as you drop them in, and bring to a boil. Turn the heat down so that the mixture bubbles gently and cook, stirring occasionally, while you cook the pasta.

Step 4

Cook the pasta in the boiling water until just starting to soften but still too hard to eat, about 2 minutes short of al dente. Take about 1/4 cup of the pasta water and add it to the sauce. Drain the pasta and toss with the sauce and 2 cups of the mozzarella.

Step 5

Pour the mixture into the prepared baking dish. Top with the remaining mozzarella and the Parmesan. Bake until the top is browned and the cheese is bubbly, 20 to 30 minutes.