Kasutera

kasutera (sometimes spelled castera) is the ‘Castella cake’ (bolo de Castela) of Japan. This sponge cake, usually very sweet, was introduced to Nagasaki in the 16th century by the Portuguese and is only made by specialist bakers, some of the oldest established of whom are still in Nagasaki. The ingredients are white wheat flour, eggs, and sugar. The texture resembles that of a steamed cake, the result of its being baked in a confined, closed space with coals above and beneath.