Place all ingredients in a 16-20 quart stockpot, and cover with 6 quarts of water.: As the cold water settles over the ingredients you will notice the colors floating and mingling, with onion skins darkening and the chicken sinking. Starting with cold water is essential because it draws out proteins and collagen steadily, which gives you a clearer, richer broth. One common mistake here is using water that s too hot, which can coagulate proteins on the surface and trap impurities, so always begin cold and give the pot a gentle swirl to settle everything evenly.
Bring to a boil, reduce heat to low, and simmer uncovered for 2 1/2 hours.: You will hear a low, steady bubble and see gentle movement across the surface as the aromatics soften and the bones release flavor. The smell will transition from raw to savory and slightly sweet, and small scum may rise; skim it occasionally for clarity and cleaner taste. Simmering at too high a heat will churn the liquid and make it cloudy, so keep it just below a boil to extract flavor slowly.
Carefully transfer the chickens to two large bowls. Remove the chicken meat from the bones and set aside.: Use tongs or a slotted spoon, feeling the skin and bones for tenderness. The transferred birds should be warm and yielding, and the bowls will collect some of the loose broth and juices. Take care to avoid splashing hot liquid; a common error is rushing this step and burning hands or losing liquid back into the pot.
After removing the meat from the bones, place the bones and the excess broth (from the bones) back into the stockpot. Season to taste – the broth should taste lightly salted.: The meat will pull away easily when the bird is cooked properly, and you should feel large pieces of white meat come off in whole segments. This reserved meat is perfect for salads, sandwiches, or future soups. Avoid overhandling it under hot water which can make it stringy; instead let it cool just enough to shred comfortably.
Continue cooking the chicken broth another 1 1/2 hours.: Returning the bones concentrates flavor as the pot continues to simmer, and tasting now helps you decide if more salt is needed. You want a gentle saltiness because the broth will reduce further. A common mistake is overseasoning at this stage, which makes final dishes too salty after reduction.
While the broth reduces, cut or shred the chicken meat and save for other meals. (It freezes beautifully.): During this phase the stock will deepen in color and develop more body, with faint steam carrying a roasted aroma. You may hear a softer simmer and notice the liquid reducing, which intensifies flavor. Watch for excessive reduction which can overconcentrate salt and fat; add a splash of water if it is dropping too quickly.
After the broth is finished cooking, strain it through a colander, and discard the remaining solids.: The meat s texture will be tender and fragrant, and handling it while the broth cooks lets you keep busy without rushing the pot. Shredded chicken will be moist and ready to use in many dishes, and freezing portions is a great way to preserve it. A mistake people make is shredding the meat too finely, which can make it dry when reheated, so keep pieces reasonably sized.
Refrigerate the broth overnight, then remove the surface fat the next day.: Pouring the broth through a colander will separate the liquid from bones and vegetables, leaving you with a clear, aromatic stock. You will notice a golden clarity and concentrated aroma after straining. Be careful when pouring to avoid splashes; using a ladle and working in batches helps maintain control.
The broth will be slightly gelatinous, but it will liquefy and add a rich, lovely flavor when heated.: As the liquid cools it will set slightly and fat will rise to the top, allowing you to skim it off cleanly with a spoon. The chilled broth also lets flavors settle and the texture become slightly gelatinous, which is a great quality indicator. A common oversight is trying to remove the fat while still hot, which is messy and less effective, so patience here makes for a cleaner final product.
The broth will be slightly gelatinous, but it will liquefy and add a rich, lovely flavor when heated: When you reheat a chilled portion you will see it melt and the aroma will return with renewed intensity, showing the broth s concentration of collagen and flavor. That gelatinous quality signals success; it adds mouthfeel and body to soups and sauces. Don t mistake the unset gelatin for spoilage; it s a sign of a well made stock, not a problem.