Step 1Use two deep pans and put one chicken into each. Into each pan, pour 2 1/4 cups water, bring to a boil and remove the scum; add two chopped onions, 1 teaspoon cinnamon, one-half teaspoon ginger and one-half teaspoon saffron. Add salt and pepper and simmer, covered, for about 1 hour, turning the chickens occasionally.
Step 2Lift out the chickens and, when cool enough to handle, remove the skin and bones and cut the meat into medium-size pieces.
Step 3Pour the chicken stock with the onions into one pan only and reduce it by boiling it down until it becomes a thick sauce, about 45 minutes. Skim off excess fat. Stir in 4 tablespoons (one-half stick) of butter, the honey and orange blossom water, if using, and cook a few minutes more. Taste; add salt and pepper if necessary. Add the parsley and cilantro, and return the chicken pieces to the sauce. All this can be done in advance and reheated when you are about to serve.
Step 4Fry the almonds in the oil until lightly browned, stirring, then drain them on paper towels. Coarsely chop, or crush them with a mortar and pestle.
Step 5Just before serving, break the vermicelli into small pieces by crushing the nests in your hands. Cook the noodles in rapidly boiling salted water for 5 minutes, until al dente, stirring vigorously at the start so that the threads do not stick together in lumps. Drain very quickly and then pour them back into the pan. Stir in the remaining butter, cut into small pieces, and some salt.
Step 6Put the chicken with its sauce into a very large, deep, round serving dish. Cover with a mountain of vermicelli, and decorate with lines of the remaining cinnamon, powdered sugar, if using, and chopped almonds emanating from the center like rays.