Cassell's dictionary of cookery

We all know the difference in the taste of a piece of pie-crust before it is baked and afterwards — one tastes of the flour, the other has a rich taste altogether different. Just such is the difference between ordinary butter and flour and brown thickening. In making thick mock-turtle soup, brown thickening is used to impart that rich flavour which is the characteristic of all thick soups. It would be a most instructive experiment to a young cook if she has a trustworthy taste to try the difference in the flavour of a little good stock or soup ; the one thickened with ordinary butter and flour raw, and the other with brown thickening, which we will now describe how to make at somewhat fuller length than would be justifiable in a receipt which, as we have before said, necessarily presupposes a certain amount of knowledge. Suppose, then, a cook to possess some fine dry flour — say half a pound — the same quantity of butter, an enamelled stewpan, a clear brisk fire, and an onion. First place the butter in the stewpan, and melt it till it runs to what cooks call oil. It will be found that there is a white scum at the top, and a milky sediment at the bottom — recollect, melt the butter, but do not boil it — simply melt it. Skim the frothy top, and pour off what may be called the clarified butter, leaving the milky sediment in the pan. Now you have got rid of what is often called the milk in the butter. Next take the stewpan, and having wiped it clean, pour back the clarified butter into it, and gradually mix in the dried and sifted flour : this will make a sort of pudding, which will all cling together, and will not — or ought not if proper care has been taken to follow these directions — cling to the stewpan. Keep this pudding over the fire, and keep stirring with an iron or wooden spoon till it begins to change colour — i.e., it will gradually from being almost white turn to the colour of underdone pie-crust or the covers of those old-fashioned books which treat of mediaeval times. As soon as the colour begins to change, redouble the stirring, and occasionally remove the stewpan from the fire for a few minutes altogether, in order that the flour should not be fried brown too quickly, for this is really all that is being done. It will be found that the butter and flour will go on boiling in the stewjjan for a long time after it has been removed from the fire — ten minutes or more : such is the power enamelled stewpans possess of retaining the heat. Have ready, close at hand, two slices out of the centre of a good-sized onion about a quarter of an inch thick. Keep stirring the butter and flour till it is of a light brown colour, not quite so brown as ripe corn, then take the stewpan off the fire, throw in the two slices of onion, which have the double advantage of slackening the heat and of imparting a rich flavour to the thickening. This will cause a great spluttering, and care should be taken to avoid a few little splashes on the backs of the hands. Keep stirring the mixture till all bubbling has ceased, and this will be longer than many would imagine. Pour off what will now be a rich brown fluid, which will assume the appearance of light chocolate when cold, into a deep dish — old marmalade pots are as good as anything — for use. It will keep for months, and is always at hand for thickening gravy.