Old-fashioned Chicken Fricasse

2½ to 3 lbs of cut-up frying chicken
1 thinly sliced onion, carrot, and celery stalk
4 Tb butter
½ tsp salt
1/8 tsp white pepper
3 Tb flour
3 cups boiling white chicken stock, white stock, or canned chicken bouillon
1 cup dry white wine or 2/3 cup dry white vermouth
A small herb bouquet: 2 parsley sprigs, 1/3 bay leaf and 1/8 tsp thyme tied in washed cheesecloth
16 to 20 white-braised onions
½ lb. fresh mushrooms stewed in butter, lemon juice, and water
2 egg yolks
½ cup whipping cream
Salt and white pepper
Drops of lemon juice
Pinch of nutmeg
1 to 2 Tb softened butter
Sprigs of fresh parsley

Preliminary cooking in butter: Dry the chicken thoroughly in a towel.
Cook the vegetables slowly in the butter for about 5 minutes, or until they are almost tender but not browned (260 degrees for an electric skillet). Push them to one side. Raise heat slightly (290 degrees), and add the chicken. Turn it every minute for 3 or 4 minutes until the meat has stiffened slightly, without coloring to more than a light golden yellow.
Lower heat (260 for an electric skillet), cover, and cook very slowly for 10 minutes, turning the chicken once. It should swell slightly, stiffen more, but not deepen in color.
Adding the flour:
Sprinkle salt, pepper, and flour on all sides of the chicken, turning and rolling each piece to coat the flour with the cooking butter. Cover and continue cooking slowly for 4 minutes, turning it once.
Simmering in stock and wine: Remove from heat and pour in the boiling liquid, shaking casserole to blend the liquid and flour. Add the wine, the herb bouquet, and more stock, or water, so the liquid just covers the chicken. Bring to the simmer. Taste for seasoning, and salt lightly if necessary.
Cover and maintain at a slow simmer for 25 to 30 minutes (180 to 190 degrees for an electric skillet). The chicken is done when the drumsticks are tender if pinched and the chicken juices run clear yellow when the meat is pricked with a fork. When done, remove the chicken to a side dish.
The sauce:
While the chicken is cooking, prepare the onions and mushrooms. Add their cooking juices to the chicken cooking sauce in the next step.
Simmer the cooking liquid in the casserole for 2 to 3 minutes, skimming off fat. Then raise heat and boil rapidly, stirring frequently, until the sauce reduces and thickens enough to coat a spoon nicely. Correct seasoning. You should have 2 to 2½ cups.
Blend the egg yolks and cream in the mixing bowl with a wire whip. Continue beating, and add the hot sauce by small tablespoonfuls until about a cupful has gone in. Beat in the rest of the sauce in a thin stream.
Pour the sauce back into the casserole, or into an enameled or stainless steel saucepan (do not use aluminum). Set over moderately high heat and, stirring constantly, reach all over the bottom and sides of the casserole, until the sauce comes to a boil. Boil for 1 minute, stirring.
Correct seasoning, adding drops of lemon juice to taste, and a pinch of nutmeg. Strain the sauce through a fine sieve.
Final assembly:
Arrange the chicken, and the onion and mushroom garniture, in the casserole. Pour the sauce over it.
Except for reheating, and the final buttering of the sauce, the dish is now ready and can wait indefinitely. To prevent a skin from forming over the sauce, spoon over it a film of cream, stock, or milk. Set it aside uncovered.
Reheating and serving: Set casserole over moderate heat and bring to the simmer. Cover and simmer very slowly for 5 minutes, or until the chicken is hot through, basting it frequently with the sauce.
Off heat and just before serving, tilt casserole, add enrichment butter, and baste the chicken with the sauce until the butter has absorbed into it.
Serve the chicken from the casserole; or arrange it with the onions and mushrooms on a hot platter, surrounded with rice or noodles, and covered with the sauce. Decorate with sprigs of fresh parsley.