Melt the butter in a large Dutch oven or soup pot over medium heat.
Add the onion, carrots, and celery, then cook for 5 to 6 minutes until the vegetables begin to soften.
Stir in the garlic, Italian seasoning, rubbed sage, kosher salt, and pepper, then cook for 30 seconds.
Sprinkle the flour over the vegetables and stir for 1 minute so the flour coats the vegetables evenly.
Slowly pour in the chicken broth while stirring, then add the chicken breast to the pot.
Bring the soup to a simmer and cook for 18 to 22 minutes, or until the chicken reaches 165°F and is tender.
Remove the chicken, shred or chop it, then return it to the pot.
Add the tortellini, peas, and corn, then simmer for 4 to 6 minutes until the tortellini is tender.
Reduce the heat to low, stir in the heavy cream and Parmesan, then mix until smooth and creamy.
Stir in the balsamic vinegar, adjust salt and pepper, and serve warm.