Make the Soup
Begin by shredding the rotisserie chicken meat. Place the meat in a bowl to the side. Remove the skin and fat and discard. Place the bones in a large stockpot.
Add the cartons of chicken stock to the bones in the stockpot and bring to a boil. Once boiling, immediately reduce to a simmer. Add in the fresh rosemary and thyme. Simmer the stock for as long as 2 hours or as little as 20 minutes (the time does add to the flavor). Strain the stock through a colander into a large bowl and reserve for the soup. Discard the herbs and bones.
Next, add the butter to the stockpot. Add in the leek and carrot. Season with salt and pepper, then saute on medium heat for about 5 minutes until softened.
Return the fortified stock to the stockpot to cover the veggies and bring to a boil. Immediately after boiling, reduce heat to simmer and cook until the carrots are tender (about 15-20 minutes).
In the last 10 minutes of cooking, add in the shredded chicken and baby spinach leaves.
In a separate pot, boil tortellini according to the package instructions then strain and add to the soup.
Finish the soup with lemon zest, heavy cream and Parmesan. Stir to combine, then salt to taste and enjoy.