The latest sweets trend in Tokyo is boko castella, and the Three Amigos blog (in Japanese) has a cool video showing off the delicious cake. Castella-style cakes originated in Portugal but have become quite popular in Japan. Its texture is similar to pound cake's, and as with molten chocolate cakes, the castella's edges encase creamy rich dough. The center of the cake is collapsed, hence the name "boko" (sunken). One popular shop serving this is Hare no Hi (in Japanese) in Azabu-Juban. If you're nowhere near Tokyo, though, and have a castella craving, here's are two helpful discussions on how to make the best honey castella and green tea castella.