Heat olive oil in a large pot over medium heat. Add Italian sausage and cook for 5-7 minutes until browned.
Add diced onion and minced garlic. Sauté for 3-4 minutes until onion is translucent. Stir in Italian seasoning, salt, and pepper.
Pour in chicken broth and diced tomatoes. Bring to a boil, then add ditalini pasta. Reduce heat and simmer for 10 minutes until pasta is al dente.
Stir in heavy cream, chopped spinach, and grated Parmesan cheese. Cook for an additional 2-3 minutes until spinach wilts and cheese melts.
Taste and adjust seasoning. Serve hot, garnished with extra Parmesan cheese if desired.