Hi Jenny,
eggs are the one thing I haven't been able to test a solid substitution for
as of
yet since the cake is pretty delicate even with them... I don't think flax
egg will be binding enough, you'd probably be better adding 2 Tbsp psylum husk plus 1/2 c liquid (mix the psylum through the flour, mix the liquid into the batter) or using one of those
egg replacers that have a potato starch base and following the instructions on the packet.