Leave the chicken on its right side. Reduce oven temperature to 350F. Leave it for a total of 15-20 minutes, basting it at least every 10 minutes. Salt the chicken, turn it on its other side, and cook another 15-20 minutes, basting at least every 20 minutes. Turn the chicken breast up and continue basting every 10 minutes during the last few minutes it is roasting. TO TELL IF THE CHICKEN IS DONE: Prick the thickest part of the drumstick with a fork. If the juices come out clear yellow, it is done. If not, roast another 5 minutes and test again. As a final check, lift the chicken and drain the juices from its vent into the pan; if the last few drops are clear yellow, it is definitely done. Put the chicken on a warm platter, remove the trussing string, and let it sit at least 5-10 minutes before carving so that the juices will not retreat into the tissues. It can wait a good 30 minutes with foil over it. As the chicken roasts, wipe the mushrooms clean with a paper towel, cut off the ends and slice them; if small, leave whole. Bring 1/4 cup water to a boil with 1/2 tablespoon butter, lemon juice and salt. Add mushrooms, cover and cook for 8 minutes. Separate the cooking liquid and save it. Pour the cream and cornstarch and cream mixture into the mushrooms. Simmer for 2 minutes. Taste and correct seasoning and hold. When the chicken is done, remove it to its platter and remove all but 2 tablespoons of fat from the pan. Stir in the shallots and saute for 1 minute. Add the port and mushroom juices and reduce rapidly while deglazing the pan (scraping up the coagulated juices) until the liquid has reduced to about 1/4 cup. Add the mushrooms and cream. Simmer for 2-3 minutes, allowing the liquid to thicken slightly. Taste and correct seasoning; add more lemon juice to taste. Butter the inside of a casserole with butter; rapidly carve the chicken into serving pieces and sprinkle lightly with salt. Arrange it in the casserole for serving. Warm the cognac carefully, do not let it catch on fire. Set the chicken over moderate heat until you hear it begin to sizzle; pour the cognac over it and ignite it carefully with a match. Shake the casserole slowly till the flames have subsided. Pour the mushroom mixture over the casserole, basting the chicken. Cover and let it steep for 5 minutes. Do not allow the sauce to boil. Serve immediately. ----