Heat the oil in a pot over medium heat. Add the garlic and cook for 2 minutes. Add the sun-dried tomatoes, tomato paste, and onion' saute until tender, 3 to 4 minutes.
Add the chicken stock, heavy cream, Italian seasoning, and salt and pepper to taste. Bring to a boil, reduce heat, and simmer for 15 minutes.
Add the tortellini and spinach, and cook for 3 to 4 minutes if using fresh tortellini, or 7 to 8 minutes for frozen.
Garnish with Parmesan cheese and serve immediately.