Heat a large skillet over medium-high heat. Add the Italian sausage and use a wooden spoon to break it into small pieces. Cook for 5-7 minutes, or until the sausage is browned and cooked through. Drain any excess grease using a colander or slotted spoon.
Add the minced onion and minced to the skillet with the cooked sausage. Sauté over medium heat for 1 minute.
Lower heat to medium and pour in the heavy cream, softened cream cheese, and chicken broth. Stir constantly until the cheese melts and creates a smooth, creamy sauce. (See note below for another option)
Add the fire-roasted diced tomatoes (undrained) and simmer for 5 minutes to blend the flavors.
Stir in the cheese tortellini pasta and cook according to package directions until al dente. Avoid overcooking, as cooked tortellini should have a pillow-like shape and tender texture.
If using baby spinach, add it at the last minute of cooking and stir until it is wilted.
Remove from heat and season with salt and black pepper to taste. Serve with garlic bread or homemade dinner rolls for a complete meal!