In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté until translucent, about 5 minutes.
Add the minced garlic and cook for an additional minute until fragrant.
Add the Italian sausage to the pot, breaking it apart with a spoon. Cook until browned and cooked through, about 7-10 minutes. Drain excess fat if necessary.
Pour in the chicken broth and diced tomatoes, then bring the mixture to a boil.
Stir in the ditalini pasta and Italian seasoning. Reduce heat and let it simmer for about 10 minutes, or until the pasta is al dente.
Lower the heat and stir in the heavy cream and grated Parmesan cheese. Mix until the cheese is melted and the soup is creamy.
Add the chopped spinach and cook for an additional 2-3 minutes until the spinach is wilted.
Season with salt and pepper to taste.
Serve hot, garnished with fresh parsley.