Heat the olive oil in a large 4-6 qt. pot over medium-high heat and then saute the onions, garlic, sausage, and any other vegetables until soft, about 2 minutes.
Add tomato sauce, tomatoes, water, seasonings, and olives if using. Increase heat to high, bring to a boil, lower heat to medium-low (or needed to maintain a low boil) and cook, covered, for 10 minutes.
Add pasta, stir well to make sure pasta is covered with sauce and cook, covered, another 10 minutes until pasta is tender (al dente). You may need to adjust heat up to maintain a low boil for the pasta.
Uncover pot and stir in cream and spinach. Cook another 2-3 minutes until heated through.