I discovered these whilst on holiday (also during the day trip to Aix-en-Provence: I love that town!)
A speciality of Aix, Calissons are a kind of almond shaped petit four. They consist of a fruit paté made from almonds, glacéd melon, and orange peel, which is then topped with icing. They melt in your mouth and are quite moreish.
I am not sure if they are easy to find outside of France, but if you do see them they are worth a try!