Layered Chocolate Cake

I am not quite sure why this delicious chocolate cake is called by the name of Surabaya, a coastal city in East Java. This recipe was given to me by an Indonesian friend in London, under that name. Since most Indonesian cake and bread recipes originated from the Dutch, my guess is that a bakery in Surabaya was once famous for this particular cake. We use cocoa for the chocolate layer, but in England I use cooking chocolate.