In French pâtisserie, Joconde is the almond sponge cake often used as a base for layered entremets.
Usually called biscuit Joconde, it is a thin, flexible sponge made with ground almonds, eggs, flour, sugar, and whipped egg whites. The almond-rich batter gives it a tender texture and enough resilience to be baked in sheets, soaked with syrup, cut into shapes, and layered with creams, mousses, ganache, or fruit fillings.
Joconde is especially famous in opera cake, where thin sheets are combined with coffee syrup, coffee buttercream, chocolate ganache, and a chocolate glaze. It is also useful in other entremets because it can form a stable base or insert without becoming as heavy as some richer cakes.
The main mix-up is with génoise, another French sponge that relies primarily on aerated eggs and flour and usually lacks the defining almond component. Financier is a small almond cake enriched with browned butter, while dacquoise is a meringue-based nut sponge. Joconde is the specific almond sheet sponge associated with layered pastry construction.