My daughter found this recipe online and I wish I was able to credit where she found this recipe, because this was absolutely amazing. THIS MAKES A-LOT......
1 pound box penne pasta
1 medium onion, chopped
4 cloves garlic, minced
2 Tb olive oil
4 - 14 oz cans Italian seasoned tomatoes, undrained
16 ounces fresh spinach
1/4 tsp red pepper flakes
3/4 tsp salt
1/2 tsp pepper
1 C freshly grated parmesan cheese
8 oz mozzarella cheese, cubed
Cook your pastain salted water according to the package directions, then drain and set aside. Do not rinse the cooked pasta!
In a large skillet, heat the oil over medium high heat and when hot, add the onion. Sauté until the onion is beginning to soften, then add the garlic and cook for another 1 minute. Add the un-drained Italian tomatoes, red pepper flakes, salt and pepper. Allow the sauce to simmer and reduce for about 15 minutes, until the sauce thickens. Add the spinach in large handfuls, mixing it in after each handful. Allow the spinach to wilt a bit and then add another large bunch of spinach, repeating until all the spinach has been added. Add 1/3 C of the Parmesan cheese and mix it in before pouring the sauce over your cooked pasta.
Before tossing the sauce with the pasta, add the cubed mozzarella cheese then combine until the sauce and cheese is evenly distributed. Transfer the pasta to a greased large casserole dish then sprinkle on the remaining parmesan cheese before placing under the broiler until the cheese browns on top