Eclairs are typically filled with a sweet vanilla cream known as crème chantilly and topped with chocolate or coffee icing. If you wish, you can make them extra rich and fill them with a combination of crème chantilly and pastry cream (crème patissière), as for Croque en Bouche. Eclairs can be prepared in advance: once the unfilled pastries are cooked and cooled, they can be kept in an airtight box for a few days or frozen, although it is best to make the chantilly cream on the day that you are planning on eating the éclairs. Makes about 25 eclairs.
Coffee glacé icing: Use coffee glace icing instead of chocolate.