This is the first recipe Yashim cooks in The Janissary Tree, and his friend Palewski guesses what it is by sniffing. You can also make it with duck, or pheasant, after which it is named in Persian Fesenjan.
Toast the walnuts in a dry frying pan over a fairly hot hob. Stir them until they catch, then cool them down and grind them fairly fine in a blender or pound in a mortar.
Melt half the butter and oil together, and brown the chicken with a pinch of salt. Remove to a plate.
Put the rest of the oil and butter in the pan, lower the heat, and fry the onions to translucency: if they brown a little, so much the better. Return the chicken and cover with the stock (or water). Bring to a boil, then lower the heat again and simmer, covered, for 30 minutes.
Add pomegranate molasses, ground walnuts, sugar and all the spices. Replace the cover and simmer for an hour, with the occasional stir to stop the walnuts sticking to the bottom.
Garnish with pomegranate seeds, and serve with a fresh salad and rice.