I wondered if molten chocolate cake could be served on Shabbat, so I tired it and it worked beautifully.
I used a recipe from the Times http://dinersjournal.blogs.nytimes.co...
and set the ramekins at the coolest corner of the blech, where they waited politely through shul and dinner. The centers were moist, gooey, not quite as "melted" as I have had it before. Probably because I left them in the oven a minute too long. But possibly from waiting on the blech for 3 hours.
I'll definitely do this again.