Heat olive oil in a large pot or Dutch oven over medium heat. Add the Italian sausage and cook, breaking it up with a spoon, until browned. Drain excess grease.
Add the chopped onion to the pot and cook until softened, about 5 minutes. Add the minced garlic and cook for 1 minute more until fragrant.
Pour in the chicken broth and diced tomatoes (with their juice). Stir in the Italian seasoning, salt, and pepper. Bring the mixture to a simmer.
Reduce heat to low. Add the cubed cream cheese and stir constantly until it melts completely into the broth, creating a creamy base.
Stir in the heavy cream. Increase the heat slightly to maintain a gentle simmer.
Add the refrigerated tortellini to the soup. Cook according to package directions, usually 5 to 7 minutes, until the tortellini float and are cooked through.
Stir in the fresh spinach until it wilts into the soup, about 1 minute.
Serve immediately, topped with grated Parmesan cheese.
Notes
For a richer flavor, brown the sausage well before adding the onions.
If you prefer chicken, substitute the sausage with 1 pound of cooked, shredded chicken breast.
This recipe is excellent for meal prep; store leftovers in an airtight container in the refrigerator for up to 3 days.