This classic French cake, the cornerstone of numerous gateaux, is very light. It is a little trickier than most of my other cakes, but provided the recipe is followed closely it should be as light as a feather. I have used no butter (except for the tin) so it does not keep well; eat it on the day it is made. If you like, try sprinkling a couple of spoonfuls of liqueur or syrup over the cake when it is cold. Use whatever you have, maybe Cointreau or cassis.