A quillet is a small, round sponge cake.
To make a quillet, sugar and eggs are beat over low heat until thickened, then removed from the heat. Flour and melted butter are then added.
It’s baked in round cake tins, then cooled. The cakes are filled with a buttercream. You decorate with a piping of the same cream and sugar on the top.
Quillet were invented in a pastry shop run by a man named Charabot [this is all we have been able to determine to date.]