Bring a large pot of water to a rapid boil and salt generously.
Cook the pasta according to packaging instructions or al dente.
Preheat oven to 500 degrees.
In a large skillet over medium-high heat, cook the onions until translucent.
Stir in the fresh minced garlic and red crushed pepper and cook for an additional 20 seconds.
Stir in the crushed tomatoes and season with oregano, salt, and pepper.
Reduce the heat to medium-low and cook for 15 minutes.
Finely chop the fresh spinach.
In a large bowl, combine the ricotta, granulated garlic, salt, pepper, spinach, and half of the parmesan cheese.
Add the cooked pasta to the sauce and stir until well combined.
Add the ricotta mixture to the pasta.
Stir in the buffalo mozzarella and check for seasoning.
Place the pasta in a casserole dish and top it off with shredded mozzarella cheese and the remaining parmesan cheese.
Bake for 10 minutes or until the cheese is completely melted.