Obtain a sponge cake. Darken it by placing it in shadow, well away from any of the sunâ€™s rays which may be shining pitilessly into your kitchen domain. Further darkening of the cake can be accomplished by rubbing into it charcoal or play-soot.
Now empty the contents of a sachet of cuppasoup into a bowl. I know it is called cuppasoup, not bowlasoup, but just do as I advise. You can choose whatever flavour of soup you desire, but do ensure that it is one heavy with croutons. In fact, however many croutons are present in the sachet, add further croutons. If you do not have access to a supply of croutons, obtain something hard, like a block of wood or an empacture of dried-up mud, and cut it into tiny crouton-sized cubes.
Boil a kettle. Pour the boiled water into the bowl, sufficient to cover the powdered cuppasoup and the croutons and the added croutons. Remove the darkened sponge cake from the shadows, and crumble it into the soup.
Stir and allow to sit undisturbed on a counter until cold. Protect it from the depredations of domestic pets, creeping vermin, and wild animals by surrounding the bowl with electrified chickenwire.
For serving, pour the soup out of the bowl into an upturned potterâ€™s cap, and use as a source of dunkage for digestive and other biscuits. When you, and your biscuits, are exhausted, pour the dregs of the soup into a drainage ditch, clean out the cap with soapy, soapy water, and return it to the potter.