For the Stock:
Place the chicken and vegetables in a large stockpot over medium heat. Pour in only enough cold water to cover (about 3 quarts); too much will make the broth taste weak. Toss in the thyme, bay leaves, and peppercorns, and allow it to slowly come to a boil. Lower the heat to medium-low and gently simmer for 1 to 1 1/2 hours, partially covered, until the chicken is done. As it cooks, skim any impurities that rise to the surface; add a little more water if necessary to keep the chicken covered while simmering.
Carefully remove the chicken to a cutting board. When its cool enough to handle, discard the skin and bones; hand-shred the meat into a storage container and put in the fridge.
Carefully strain the stock through a fine sieve into another pot to remove the vegetable solids. Store the stock, place the pot in a sink full of ice water and stir to cool down the stock. Cover and refrigerate over night. In the morning take a spoon and remove all the fat from the top.
For the Soup:
Place a soup pot over medium heat and coat with the oil. Add the onion, garlic, carrots, celery, thyme and bay leaf. Cook and stir for about 6 minutes, until the vegetables are softened but not browned. Pour in the chicken stock and bring the liquid to a boil. Add the noodles and simmer for 5 minutes until tender. Fold in the chicken, and continue to simmer for another couple of minutes to heat through; season with salt and pepper. Sprinkle with chopped parsley before serving.