Like a lot of white middle-class people of my generation, I have a few too many university degrees. My first tertiary study was an Arts degree with a double major in French which I undertook perhaps partly to legitimise my avid reading of Paris Match (and its extensive coverage of ageing French pop stars and minor European royalty). The main things I got out of those three years were two friends called Joanna and this recipe, given to us by a boy in our class. I'm not sure where he got it from - it's way more sophisticated than any 18 year old has any right to be. But he was French, so perhaps that explains it. The three of us quickly incorporated it into our baking repertoire and all these years later, it's still being made with regularity. For good reason. It's simple, elegant and utterly delicious. Somehow it manages to be both densely squidgy and light, its lemon flavour is subtle yet striking and it works equally well as a showstopping dessert or as an everyday cake, one which tastes especially fine with a cup of the inkiest black coffee. VoilĂ .