In a large Dutch oven or stock pot, heat oil over medium heat. ADD carrots, celery and onion. COOK for approximately 10 minutes, stirring frequently, until onion look opaque.
ADD the garlic and COOK for 1 minute.
ADD the chicken broth and bring to a BOIL. Continue to BOIL for about 10 minutes.
ADD the tortellini and mushrooms, if using, and COOK for another 4-5 minutes.
As the tortellini being to rise to the top of the pot, ADD the spinach to wilt. SERVE.