In a large pan melt the butter over a medium heat.
Roughly dice the onion, celery and carrots, add to the pan and cook until the onions soften, about 5 minutes,
Add the sage, thyme, rosemary, black pepper and bay leaf then stir through the vegetables.
Pour in the stock, turn up the heat and bring to the boil, once boiling turn down the heat and allow to simmer for 5 to 10 minutes.
Shred the chicken, add to the pan and allow the stock to come back up to a simmer.
Add the pasta, stir through and cook for the recommended cooking time.
Check the seasoning and add salt and pepper to taste.
This is a pretty simple dish so it's the quality of the stock used that really makes it, if you can't get hold of a decent chicken stock use a cheap "stock pot" and add a small amount of oyster sauce and dark soy sauce to give it a richer flavour.