Place a large pot or Dutch oven over medium-high heat. Add the Italian sausage and cook, breaking it apart with a wooden spoon, until browned and cooked through, about 6 to 8 minutes. Drain excess grease, leaving about 15 ml in the pot.

Reduce the heat to medium. Stir in the diced onion and cook for 4 to 5 minutes until translucent and soft. Add the minced garlic, Italian seasoning, and red pepper flakes, cooking for an additional 1 minute until highly fragrant.

Pour in the chicken broth and the diced tomatoes with their juices. Stir well, scraping up any browned bits from the bottom of the pot. Bring the mixture to a rolling boil.

Stir in the ditalini pasta. Reduce the heat to medium-low to maintain a gentle simmer. Cook uncovered, stirring occasionally to prevent sticking, until the pasta is al dente, about 10 minutes.

Reduce heat to low. Whisk in the softened cream cheese, heavy cream, and grated Parmesan cheese until completely melted and the broth becomes smooth and creamy.

Add the fresh baby spinach and stir until it wilts completely into the soup, about 1 to 2 minutes. Taste and season with salt and black pepper as desired. Remove from heat and serve hot.