This is an adaptation of the chicken stock recipe from Thomas Keller's beautiful cookbook Bouchon.
(correction: I thought it was an adaption; it's not really. But the book is lovely anyway.)
Both the bones for making this stock and the finished stock can be frozen. I usually throw chicken bones in freezer bag when I roast a chicken, and then freeze finished stock in ice cube trays and then in plastic bags, which makes convenient units for defrosting.
It's important that the water you start with is cold. The rule is that if you want the ingredients to flavor the liquid, start the liquid cold; if you want the liquid to flavor the ingredients, start the liquid hot. Obviously, we're going for the former here.
2-3 chicken carcasses, including giblets
1 stalk celery
1 medium onion
2-3 pieces fresh thyme
1 bunch parsley stems
1 or 2 parsnips (optional)
Place the chicken parts in a very large stock pot & fill with cold water. Place over medium-high heat, uncovered, and raise to a boil. Reduce heat to simmer.
The key for good clear stock is to skim all the scuzz and foam off the top frequently (I usually wander into the kitchen and check every 5 or 10 minutes). Don't worry about losing a few tablespoons of broth at the same time; the trade-off is worth it.
Continue to simmer the broth until it remains clear after a few wander-in intervals (only very little foam appears around the edges of the pot). Cut the vegetables into chunks (leave the skin on the onion) and add to the pot along with the herbs. Simmer for another 30 minutes or so - at this point you can just start tasting the broth to see how it's coming along. It should be flavorful but not too dense. You'll also notice that there's no salt in this recipe; if you want more flavor feel free to cook it down more, but not adding salt means you won't risk altering the flavor of recipes in which you use it. And it tastes really delicious without it, anyway. One final word of advice: don't leave the carrots in too long. I did that once and my broth tasted like nothing but carrots.
When the broth tastes right, turn off the heat and remove the bulk of bones & vegetables with tongs, get the rest with a slotted spoon. Let the broth cool a bit.
Most recipes will tell you to strain broth through cheesecloth, but I don't know anyone who actually keeps cheesecloth around. I use a strainer over a bowl with a single sheet of paper towel in the bottom - it takes awhile for the broth to strain through, but you'll catch any little gritty pieces in the towel. Once strained, ladle into ice cube trays and freeze. Cubes can be stored in plastic bags in the freezer once solid.