I was having some people round for coffee and cake. One cake I was making - in a hurry, with JUST enough time before they would arrive - was ginger sponge. When the timer went and I opened the oven, instead of the two layers I was expecting to see, I'd got two thin discs of sort of brandy-snap material, crispy and with little holes every so often. Mental rewind gave the explanation - I HADN'T ADDED ANY FLOUR.
With no time to cook another cake, I chopped some lemon-rind very small, mixed it into whipped cream, and used that to sandwich the two bits. I announced it as 'ginger and lemon crisp' and served it with spoons. It was a bit messy to eat, but was all polished off, with people asking for seconds, and the recipe!