Combine the stock, chicken, and gravy in a large pot over medium heat.

Meanwhile, heat the olive oil in a skillet over medium high heat. Then add the onion. Cook for 2 minutes, and then add the mushrooms, and generously salt and pepper. Stir to evenly coat in the olive oil. Then add ⅓ cup of the warm broth from the pot to the skillet. Sauté for 6 minutes, or until the mushrooms have absorbed all of the liquid.

Add the sautéed mushrooms and onions to the broth. Then add the spinach and green beans. Let the soup come to a low boil, and then add the tortellini and cook for the amount of time specified on the package of tortellini. Serve once the tortellini is floating. Any extra soup can be frozen.