In a 5 qt or 6 qt stock pot, add thawed chicken breasts and 2 tablespoons butter. Cook until golden brown on both sides. Remove from pot and shred the chicken.
Add in the remaining 4 tablespoons of butter, onions and garlic. Heat until the onions are translucent.
Whisk in the flour and form a rue.
Add in the rosemary, thyme, broth, potato, peas, carrots, and salt and pepper.
Cover and cook on low heat for 30-40 minutes or until the potatoes are tender and cooked.
Stir in the heavy cream and allow the soup to heat on low for an additional 10 minutes.
Serve.