Quarter and core the apples, then peel them, and put them at once into a basin of cold water; this will help preserve the colour. Next lift the pieces of apple into an enamel-lined pan, add enough boiling water to just show among the pieces. Put the lid on the pan, and let the apples cook quickly, stirring them now and then with a silver fork; on no account use an ordinary metal kitchen fork. Add the butter and sugar to taste. Stir over the fire until the sauce is quite hot and carefully mashed. Serve it in a hot tureen.
N.B. - If the sauce is at all lumpy, it may be necessary to rub it through a sieve; but avoid this, if possible, for the sake of the colour.