Step 1

Preheat your oven to 375 degrees Fahrenheit. Spray a 9 by 13 inch baking dish with cooking spray. Set aside.

Step 2

Place a large pot of water over high heat to boil the rigatoni. Once the water is at a roaring boil, season it with salt and add the noodles. Boil the noodles for two minutes less than the time stated on the box. Drain the pasta and set aside.

Step 3

While the pasta is boiling, place a large skillet over medium-high heat. Heat the olive oil for 30 seconds before adding the garlic and red pepper flakes. Cook until fragrant, about 30 seconds, and then add the sausage. Break up the sausage as it cooks.

Step 4

When the sausage is no longer pink, add the sliced mushrooms. Cook for 3-4 minutes until softened.

Step 5

Add the diced tomatoes, stirring to combine. Stir in the basil and oregano. Bring the sauce to a boil, and then reduce to a simmer. Simmer for 5 minutes, stirring occasionally.

Step 6

Add the spinach to the sauce, allowing it to wilt.

Step 7

In the casserole dish, combine the noodles, and the sauce. Stir in 1 cup of the shredded mozzarella. Then stir in a second cup. Stirring it in in 2 groups will prevent it from melting too quickly, preventing it from being evenly distributed throughout the casserole. (Alternatively, combine all of this in the skillet if it is oven-proof.)

Step 8

Add the remaining two cups of mozzarella and the parmesan in an even layer over the top. Bake uncovered for 20 to 25 minutes or until the cheese on top is bubbly and beginning to brown. Serve warm and enjoy!