Heat oil in skillet over medium-high heat. Add Italian sausage and cook until browned.
Stir in garlic and red pepper flakes and cook for 1-2 minutes. Season with salt and pepper to taste.
Stir in marinara sauce, oregano, and basil. Reduce heat and simmer, stirring occasionally, for 5-10 minutes.
Add water and dry pasta to skillet. Bring to a boil, stirring occasionally.
Once mixture reaches a boil, reduce heat to a low boil, cover, and cook until pasta is tender.
Stir in spinach and Parmesan cheese. Cook for 2-3 minutes, until spinach has wilted.
Remove from heat. Sprinkle mozzarella cheese over pasta and cover until cheese has melted.