Are they talking about donuts? Custard was my second-favourite, the banana creme donuts from Dunkin' Donuts were my favourite but I haven't had one of those in about two decades since all of the Dunkins remotely near me closed by the mid-2000s.
Thank you for the translation (I could go for some castellas myself. Also lo and behold S5 is coming; our collective excitement (despite each chapter advising otherwise) manifested it into existence).