Chicken Stock and Chicken Noodle Soup

This is the epitome of comfort food. Everyone needs one delicious and nutritious chicken soup recipe in their repertoire, and this version is perfect.
Combine the chicken, onion, garlic, whole carrot, whole celery stalk, bay leaf, and parsley, if using it, in a saucepan. Add 8 cups of water. Bring to a boil, then reduce the heat to allow the liquid to bubble gently but steadily.Cover and cook, stirring gently every 15 minutes or so, until the chicken is fully cooked (30-40 minutes for parts, 50-60 minutes for the whole). If necessary, add water to keep the chicken submerged. To check the readiness, carefully remove a piece of chicken with a slotted spoon or tongs and pierce it with a thin-bladed knife. You should meet no resistance, and the meat should be white to the bone and may start to fall off in places.Carefully transfer the chicken from the pan to a shallow bowl using tongs. When it is cool enough, remove the skin from it; separate the meat from the bones and cut it into small pieces. Save 2 cups for the soup, and put the rest in the refrigerator for other use. If you have time, return the bones to the pot and let the broth simmer for another 15-30 minutes.Cover a large pot with a strainer or colander and carefully pour in the broth; press down the vegetables to extract as much liquid as possible, then discard them. Remove the fat from the top. You should get about 7 cups; if not, add a little water. Sprinkle the broth with a little salt and pepper. (If you just want to make chicken broth, stop there.)Put the pan on medium-high heat. Bring to a boil, then reduce the heat so that the liquid is constantly bubbling. Add the chopped carrots and celery and cook, stirring occasionally, until the vegetables are as crisp or tender as you like (about 10-30 minutes).Add the pasta and the remaining 2 cups of chicken; adjust the heat so that the mixture is constantly bubbling, and continue cooking until the pasta is soft but not mushy (another 5-10 minutes). Taste and add the seasoning, garnish with the remaining celery leaves, and serve.