Put the previously prepared, cold, fat-free, 2-1/2 quarts of chicken stock in an 8 quart pan.
Add a whole stewing fowl or roasting chicken weighing between 4 and 5 pounds. Bring slowly to a boil.
Skim off any scum that forms on the surface; reduce heat; cover and simmer gently until the chicken is very tender, about 1 hour for a young chicken, or 2 to 2-1/2 hours for a fowl.
Remove the chicken/fowl and either serve it as poached chicken, or remove the skin, take the meat from the bones, and use it for other dishes such as chicken salad, hash, chicken pie, or creamed chicken, etc.
Strain the broth through several thicknesses of cheesecloth into a bowl; let cool, then skim off the fat.
You now have 2 quarts of beautifully rich, strong broth which can be used for cooking.
Should you want to reduce it even more, and clarify it for consomme' ... see the recipe: Chicken Consomme' by James Beard.
For chicken consomme' the broth must be absolutely fat-free and clear. Therefore, it's important that you strain the above through several thicknesses of cheesecloth, let cool, and skim off all the fat.