A few drops of lemon-juice. Cayenne.
Stamp out rounds of bread the size of the top of a wineglass, and fry them a delicate brown in butter.
Put into a basin the rest of the ingredients, and work them together with a wooden spoon till they are smoothly and evenly mixed. See that the mixture is nicely seasoned. Put it into a forcing-bag, and force it prettily on the croutons.