ladyfingers resemble fingers. ladyfingers are sponge cake batter piped and baked on a sheet pan. Wondra flour makes wonderful ladyfingers. the wonder of wondra flour is preventing the cake batter from spreading sideways when piped. cake flour and all-purpose flour make wider and flatter ladyfingers as the batter spreads sideways during piping. recipe on ROSE’S heavenly CAKES: Ladyfingers (page 264).
(note: regardless what flour you choose, i recommend mixing only 1 recipe at a time. i made a 3x recipe, only the first sheet pan of ladyfingers turned shapely, the batter quickly deflates after that, for my second and third sheet pans were not so pretty. not even a fast master baker can top this!)
ladyfingers start as whipped egg yolks and, separately, as whipped egg whites. then the two are folder together and flour added.
non-piped ladyfingers, baked in layer pans, are called biscuit de savoie. i was awarded an honorary PhD on biscuit de savoie, when i made the 12-tier Hawaii Way cake: