Bring a large pot of water to a boil and add a pinch of salt.
Preheat oven to 350 degrees.
Boil pasta until tender, usually 10-12 minutes.
For the last two minutes of pasta boiling, Add the spinach to a mesh strainer and steam it over the pot - to gently wilt.
Remove the pasta and spinach and transfer to the casserole dish.
Sprinkle the nutritional yeast over top the pasta and spinach.
Pour the pasta sauce right over top the pasta.
Sprinkle the cheese over top the sauce.
Add the chopped vegan sausage over top the cheese - you could also fold the sausage into the pasta if you want a more tender sausage texture. Sprinkling on top allows them to brown nicely with slightly crisp edges.
Add optional oregano, vegan Parm and EVOO over top.
Cover the casserole dish in foil or a lid and bake at 350 degrees for 15 minutes. If desired, remove covering for two minutes and turn oven to broil - to further intensify the melty cheese bubbling.
Serve warm!