Sorry for posting this as an answer, I would prefer to put it as a comment on the solution but due to reputation lower than 50, I couldn't.
The elected solution works just fine, and thanks for it!
But I keep thinking about one thing: I usually separate the mappings on several profiles, by entity, let's say. So here I would have a ModuleProfile with the Module to ModuleUI mapping settings and a PageProfile with the Page to PageUI mapping settings.
On this scenario, how would you do it? Would you still include the - Mapper.CreateMap<Page, PageUI>(); - on the ModuleProfile?