Finally, thanks to Cook's Illustrated, I have figured out how to make this delicious dish from Maggiano's.
If you are a lazy fuck you can skip the first few steps where you make chicken stock from the back of the chicken, and just use 2 1/2 cups canned chicken broth (use Swanson's).
FOR THE STOCK
1. With a very sharp knife, cut down the back of the chicken on one side of its backbone. Cut down on the other side and tear out the backbone. Cut off the wings where they are attached to the breasts. Set aside rest of chicken. Carefully hack up the wings and back into 1-2 inch chunks. You will have to hack pretty hard on the wing bones. Rinse and dry the blood off.
2. Add 1 tablespoon olive oil in dutch oven, heat on medium-high. Add about 1/2 - 2/3 of an onion, chopped, to the dutch oven. Saute until softened, about 3 minutes. Remove to bowl, set aside. Add hacked up chicken back and wings to pot and saute about 5 minutes, until they are golden. Add the onion back to the pot. Turn heat to low, cover tightly, and let onion and chicken sweat for 20 minutes and release their juices. In the meantime, heat about 3 cups of water to boiling. After 20 minutes, add boiling water to chicken and onion, along with bay leaf and salt to taste. Bring to boil, then simmer, partially covered, for 30 more minutes until stock is golden, rich and flavorful. Strain stock into a large measuring cup and discard solids. Set aside or refrigerate until fat congeals in thin layer on top of stock, scoop off fat with soup spoon and discard.
FOR THE REST OF THE RECIPE
3. While stock sweats/simmers, quarter the rest of the chicken (you should have two brests and two thighs/legs). If desired, brine the chicken for 30 minutes (that is to say, fill a bucket or large tupperware container with 2 quarts cold water; dissolve 1/3 cup tablesalt into bucket, add chicken and refrigerate for about 30 minutes -- this process makes chicken more juicy and flavorful). Rinse and clean and thoroughly dry chicken pieces. Sprinkle with fresh ground pepper and salt (do not use salt if you brined the chicken though).
4. In a 12-inch heavy-bottomed skillet (preferably nonstick), melt 1 tablespoon olive oil and 1 tablespoon butter over medium-high heat. Swirl to coat pan. Saute chicken pieces until golden brown, about 4-5 minutes per side. You don't have to cook it all the way through. If the skillet is too crowded, rinse out the dutch oven you used to make the stock and heat oil and butter in there, and saute some of the chicken in the dutch oven alongside the skillet. Once sauted, remove skin (you can probably eat it if you want) and set pieces in single layer in the dutch oven. Cover chicken with the stock you just made, bring to a boil and then simmer, partially covered, for 30 minutes. After 30 minutes, remove the breasts from the stock, set aside. Let dark meat simmer about 15-20 minutes. Once removed from the simmering stock, the juices from the chicken should run clear yellow, without any trace of red or pink. Reserve stock in dutch oven.
5. While chicken simmers, drain off all but a tablespoon of fat from the skillet. Heat on medium-high heat (do not rinse or scrape off anything) and add mushrooms and remaining onion and a healthy pinch of salt. Sautee about 8-10 minutes, stirring often and scraping up browned bits from the bottom of the skillet, until mushrooms and onions are soft and cooked. Add sherry/marsala and cook over high heat until most liquid evaporates. Make sure y ou scrape up all the browned bits (the fond) from the bottom of the skillet. Transfer to a bowl and set aside. Now is a good time to bring a large pot of salted water to a bowl (about 3-4 quarts) for the pasta.
6. In now empty-skillet, heat 2 tablespoons butter until melted over medium heat. Whisk in 3 tablespoons of flour and stir vigorously until combined into paste and cook for about 1 or 2 minutes, until golden. Add the cup of half and half and whisk vigorously again over medium heat for several minutes, until completely combined with butter-flour mixture without any lumps. Immediately whisk this mixture into the stock in the dutch oven over medium-low heat, stirring until smooth. Simmer over medium-low heat, stirring frequently, until sauce thickens to a heavy-cream like consistency (thick enough to lightly coat back of a spoon), about 7 minutes. Add juice from 1 lemon, minced thyme, nutmeg, and the mushroom and onion mixture to sauce. By now the chicken should be cool enough to handle. Pull apart chicken into bite size pieces and toss into the sauce too. Simmer sauce, chicken, mushrooms and oinions lightly to combine flavors. Add grated parmesan cheese if you want.
7. Put pasta in boiling water and cook until just shy of al-dente (8-10 minutes, check package for instructions). DO NOT OVERCOOK PASTA. Drain pasta well. Add pasta to the sauce, stir to combine, and let sit so the pasta soaks up the sauce. Serve, with a fresh minced parsley sprinkled over if desired, and pass around grated parmesan cheese if you want too.