I think the famous chocolate cake was the Blackout cake; apparently pretty complicated to make:
http://www.npr.org/2014/03/27/293937447/before-you-bake-brooklyns-legendary-cake-heed-a-warning
Which is why we always bought it. In the 90s they started putting them out again but given the anti-fat and sugar craze, no one bought them. So sadly, they went under again.