Stir chicken stock, butternut squash, carrots, celery, onion, wine, parsley, basil, and garlic together in a large pot; bring to a boil. Cook at a boil until squash is tender, about 1 hour.

Pour squash mixture into a blender no more than half full. Cover and hold lid in place. Pulse blender a few times before leaving on to blend. Puree in batches until smooth.

Return blended soup to pot; add bay leaves. Bring soup to a boil, reduce heat to medium-low, and cook until beginning to thicken, 30 to 60 minutes. Season soup with salt and pepper. Stir milk and cream through the soup.