In a large pot or Dutch oven, heat olive oil and butter over medium heat. Add the diced onion, sliced carrots, and celery. Sauté for 5–6 minutes until the vegetables are softened and translucent. Add the minced garlic and cook for another minute until fragrant, being careful not to burn the garlic.
Pour in the chicken broth, then add the cooked shredded chicken, dried Italian seasoning, and black pepper. Bring the mixture to a simmer and cook for 5 minutes to allow the flavors to meld together.
Add the cheese tortellini to the pot. Cook according to the package instructions, typically 4–6 minutes, until the tortellini are tender but not overcooked.
Reduce the heat to low and stir in the heavy cream to create a creamy broth. If using, add the fresh spinach and cook for another 2–3 minutes until the spinach is wilted. Taste the soup and adjust the salt if necessary.
Ladle the hot soup into bowls and garnish with chopped fresh parsley. Serve immediately for a comforting and creamy meal.
