Remove the skin from the kidneys, cut them in half lengthways, season and simply stiffen the cut surfaces only by placing in hot butter for a few moments. Using 30 g (1 oz) ordinary forcemeat mixed with a good third its quantity of dry Duxelles per 2 kidneys, fashion a small dome in the centre of a buttered dish. Surround the base of this with slices of raw mushroom and press the half kidneys into the forcemeat, stiffened sides inwards and in pairs; place a nice grooved mushroom on top of the dome. Coat the whole with a fairly thick Sauce Duxelles, sprinkle with fine breadcrumbs and melted butter and place in the oven to gratinate.
On removing the dish from the oven surround the base of the mould with Sauce Demi-glace and sprinkle the gratinated surface with a few drops of lemon juice and chopped parsley.