Don't ask me about the history and origins of Hélénettes because I don't have a clue. All I know is that they're a simple, little, almond (or sometimes hazelnut) cake that's similar to a classic, old-style macaron but uses egg yolks rather than egg whites. This recipe is based on received wisdom (with only minor tweaks) from some French bakers that I've come across. They're really easy and quick to make. They're also a good way to use up egg yolks after the egg whites have played their part in other recipes such as meringues. I like the vanilla flavour in this recipe but it could be replaced with almond extract, orange flower water or whatever else you might fancy - within reason. Alternatively, you could leave out the added flavouring altogether. You could also replace the ground almonds with ground hazelnuts if you feel like it or if you have some languishing in your cupboard.