Preheat the oven to 350 F.
Boil a large pot of heavily salted water and cook your rigatoni for 5 minutes. It will be extremely al dente.
Drain the pasta and set aside.
Pour the oil into a large heavy bottomed pan on medium high.
When the oil starts to glisten, add the pancetta. Cook for 2 minutes.
Add the mushrooms and cook for an additional 2 minutes.
Add the chopped onion and cook for 8 minutes.
Pour in the passata and cook for 5 minutes.
Add the drained pasta to the baking pan, along with the basil, spinach, mozzarella, béchamel, and salt.
Mix to combine, then sprinkle with the remaining Parmesan.
Place the pan in the oven and bake for 20 minutes.
Turn the oven to broil and cook for 5 minutes until browned and bubbling.
Allow to cool for at least 10 minutes before serving.