A couscoussier (couscoussière in French, kiskas in Arabic) is a two-part food steamer specifically designed to cook couscous. Stock or stew is heated in the bottom pan and the couscous is steamed in the top pan. Steam passes between the two vessels by means of small holes in the bottom of the top section. This both cooks and flavours the couscous.
In the UK, couscoussiers can be bought from Maroque