Heat oil in large saucepan over medium high heat until hot. Add onoins; cook and stir 2 to 3 minutes or until tender. Add garlic and mushrooms; cook and stir 2 minutes. Add broth; bring to a boil. Add tortellini and cooked cubed chicken, return to a boil. Boil 5 to 7 minutes or until tortellini are of desired doneness.

Sir in spinach. cook 1 to 2 minutes more until wilted.

To serve, spoon soup into individual bowls. Top each serving with cheese.