Ottolenghi Style Chocolate Babka

I've been salivating over producing this delicacy that hearkens back to my NYC youth for quite sometime. I cannot tell a lie - this is NOT my first attempt. I tried, and failed spectacularly, about a month ago. The doomed pair literally came out of the oven like a chocolate boat anchor - heavier, even!! The big difference between this Yotam Ottolenghi (Jerusalem Cookbook) Babka and a NY style babka is the citrus inclusion in the dough, and the overnight cold retard. This is also known in Israel as a chocolate Krantz Cake.