Bring salted water to boil in a large pot. Add pasta and cook until al dente. Drain pasta.

In a separate large pot, heat olive oil on medium heat while pasta is cooking. Add onions and cook until translucent. Add sausage, spinach and garlic. Cook until heated through.

Add Alfredo sauce to sausage mixture and bring to a boil. Add salt and pepper to taste. Take off heat.

Add pasta to Alfredo sauce and stir until combined.

Top with parmesan cheese if desired. Serve hot.