Start by heating olive oil in a large pot over medium heat. Add chopped onions and cook until they become soft and translucent. Stir in minced garlic and cook briefly until fragrant, making sure not to burn it.
Add ground beef directly into the pot, breaking it apart with a spoon. Season with salt, pepper, and Italian seasoning. Cook until the meat is browned and fully cooked, allowing the flavors to blend well.
Pour in the beef broth and diced tomatoes, stirring everything together. Bring the mixture to a gentle boil, then reduce the heat to let it simmer. This step helps develop a rich and savory soup base.
Add the cheese tortellini into the simmering soup. Let it cook according to the package instructions, usually about 5–7 minutes. The pasta will absorb some of the broth and become tender.
Lower the heat and stir in the heavy cream, mozzarella, and parmesan cheese. Mix well until the cheese melts completely and the soup turns creamy. This is where the soup gets its signature richness.
Finally, add fresh spinach and let it wilt in the hot soup. Taste and adjust seasoning if needed. Turn off the heat and let the soup rest for a few minutes before serving.