Melt butter in a large pot or Dutch oven over medium-high heat.
Add onion and carrots to the pot and sauté for 5 minutes. Add garlic and sauté for 30 seconds.
Stir in flour, thyme, and sage. Cook for 2 minutes, stirring constantly.
Pour in chicken broth, add bay leaf, salt, and pepper. Bring to a simmer and cook for 12-15 minutes, or until carrots are tender.
Add tortellini and shredded chicken to the pot and simmer for 5 minutes.
Remove bay leaf. Stir in heavy cream and Parmesan cheese. Simmer for an additional 5 minutes, or until tortellini is cooked through and soup has thickened.
Garnish with fresh parsley and additional Parmesan cheese, if desired.