This recipe is from +Jenny McGruther, modified a bit. Here's my version (but check her's out).
1. Buy a plump chicken, the best quality you can afford.
2. Place the chicken in a large crockpot, cover it completely with cold water, and turn the pot on low.
3. Lay various veggies on top: carrots including tops, whole stalks of celery including leaves (but cut in half if they won't fit), onions, leeks, kale or chard stems, or whatever is available. Don't chop them or mix them in.
4. Cover the pot and ignore it for 24 or more hours.
5. Remove the veggies and discard the inedible parts.
6. Remove the chicken and debone, carefully retaining as much of the broth as possible.
7. Turn the broth, still in the crockpot, on high.
8. Saving half the chicken for another recipe, place the boned chicken and salvaged cooked veggies into a food processor and whirr till it is almost smooth. (I had to do this in batches).
9. Add the resulting paste to the broth and stir it in thoroughly.
10. Heat till steamy.
11. Stir in a cup of heavy cream. I preheated the cream in the microwave because my crockpot is slow to heat up.
12. Mix 3-4 egg yolks (depending on size - I used duck eggs, and with their large yolks I found I needed only 2 yolks). Use a wire whisk. Add some of the hot stock mixture to temper the yolks, then stir them into the soup.
13. Heat the soup to close to a full boil.
14. Serve. I added an extra tablespoon of cream in a swirl. We ate the soup with roasted veggies (potatoes, rutabagas, and parsnips sprinkled with olive oil and good salt and cooked and browned in a 400 degree oven).
This is a smooth, rich, satisfying soup full of flavor and real food. The two of us will get two meals each out of it. The flavor is so full that more cream or even water could be added to stretch it. Thanks, Jenny!