Barefoot Contessa (en-US)

3 (5-pound) roasting chickens
3 large yellow onions, unpeeled and quartered
6 carrots, unpeeled and halved crosswise
4 celery stalks with leaves, cut into thirds crosswise
4 parsnips, unpeeled and halved crosswise
20 sprigs fresh flat-leaf parsley
15 sprigs fresh thyme
20 sprigs fresh dill
1 head garlic, unpeeled and cut in half crosswise
2 tablespoons kosher salt
2 teaspoons whole black peppercorns (not ground)

Place the chickens, onions, carrots, celery, parsnips, parsley, thyme, dill, garlic, salt, and peppercorns in a 16- to 20-quart stockpot. Add 7 quarts of water and bring to a boil. Lower the heat and simmer uncovered for 4 hours, skimming off any foam that comes to the top. Set aside until cool enough to handle. Strain the entire contents of the pot through a colander and discard the solids.

Homemade Chicken Stock