This sauce requires great care in making. Put in a saucepan 4 1/2 oz. of butter and 3 1/2 oz. of flour. Put the saucepan on a slow fire, and let the flour cook lightly without getting coloured. As soon as the flour is cooked, dilute it with the foundation of chicken, little by little, stirring all the time with a wooden spoon. So as to be able to spread it out without lumps, keep it much lighter than ordinary sauces. Stir it all the time till it boils; when remove it to side of fire, so that it should but just boil, and that only on one side. Add two or three raw chopped mushrooms; as the butter and steam rise gently to the surface, remove them, and let it cook for a good hour. Afterwards strain your sauce through a fine cullender into a frying-pan, more wide than deep. Put it on a hot fire, and stir without stopping with a wooden spoon to prevent it sticking; this is an important point. Add one or two gills of good sweet cream. As soon as the sauce sticks to the spoon, that means it is ready. Strain it through a muslin in a little bain-marie; stand the sauce to heat in a saucepan with hot water in it.

Now put the half of a white of raw egg with the chicken, mix them well together, add little by little some good thick fresh cream, and make it blend as much as possible; add three or four spoonfuls of cold Sauce Supreme, and about three gills of thick cream. Test it by dropping a little of the mixture into water. It should be soft, not too solid, and well-flavoured. Always try it before putting in all the cream, or it might become too limp, which would spoil its quality.

Butter the inside of a round cylinder-shaped mould with a hole in the centre of it. Put the mould on the ice for a moment to harden the butter. Fill the mould with the mixture up to about an inch from the rim. Tap the mould gently on a napkin folded several times to equalise the mixture and to heap it together, to prevent the holes which might form themselves inside the sponge.

Put a little boiling water in a saucepan large enough to contain your mould, cover it with a lid, put it in a very slow oven, and let it poach for twenty-five to thirty minutes. See that the water in the saucepan does not boil, for which it is necessary from time to time to add a drop of cold water. Turn out the mould onto an entree-dish; trim with one or two truffles cooked in Madeira. Cover the mould lightly with a little of the Sauce Supreme, and put the rest of the sauce in a sauce-boat.