This attempt didn't come out as good as the first one.
No.1 was too dense, so I tried to make no.2 more spongey. Unfortunately I may have gone too far the other way. It wouldn't behave, wouldn't roll, and the gloopy filling (made from a recipe in Vegan Cupcake Take Over The World, even though I didn't have any proper chocolate to make it with) wouldn't hold it together, stay put, or even solidify after ages in the freezer.
I also made this one using banana and soured soya milk instead of egg replacer, so it just tastes of banana and chocolate, which doesn't quite work for a yule log.
So it's back to the original recipe for me, provided I can remember it. I'll do fewer tweaks next time, see if I can't edge it closer to perfection, rather than try and run it home in one night.