Don't preheat oven. Sounds odd but trust me on this one.... Is a good plan to line a tin first though. Size doesn't overly matter, just your favourite basic cake pan.

Pop everything besides coffee in a bowl and attack it with a whisk until nicely smooth. Quickly fold through hot coffee and pop into tin. It is a thinner mixture, again, just trust me.

Pop it in the oven and turn it on to 160. Let it cook until a skewer comes out clean. Depending on the tin I use, it varies from half an hour (big square tin) to 45 min (standard round pan). This may be different to how long it takes at your house so be sure to keep an eye one it. Chuck on your favourite icing once cooled.