Castela and Milk
This origin is not Japan. It is said that this sweet cake was brought by Portuguese missionary priest during Muromachi Era ( 1336-1573 ). It is considered that the name of it " Castela"
was taken from " Castilla " ( Spain/ with Portuguese pronunciation )
You can buy it at small local stores and also fancier ones at department stores. I usually enjoy this with milk or green tea.
The ingredients are eggs, wheat flour and sugar.