In a large pot, heat the olive oil over medium heat. Add the chopped onion and sauté for about 3-4 minutes until translucent.
Add the minced garlic, carrots, and celery. Stir and cook for another 5 minutes, allowing the vegetables to soften.
Remove the sausage from its casing and add it to the pot. Break the sausage into smaller pieces as it cooks. Cook until browned and no longer pink, about 5-7 minutes.
Pour in the chicken broth and add the diced tomatoes, oregano, and basil. Stir to combine.
Bring the soup to a simmer and cook for 10 minutes to let the flavors meld together.
Add the cheese tortellini to the pot and cook according to the package instructions, usually around 3-5 minutes.
Finally, stir in the fresh spinach until wilted, and season with salt and pepper to taste.
Serve the soup hot in bowls, topped with grated Parmesan cheese and fresh basil leaves if desired.
Notes
Feel free to adjust the spice level by choosing sweet or spicy sausage.
Keyword comfort food, Italian sausage, soup, tortellini