If you're using cream instead of custard filling microwaving doesn't work so well ^_^; and the ones I'm thinking of I'm pretty suree are whipped cream.
I never realised there were "Asian style" creampuffs and...not O_O having only had Mum's creeampuffs and there used to be a bakery at a nearby shopping centre that had them (I would buy them whenever I saw them but I haven't been past there for a while) that had similar style (soft and full of cream) it never occurred to me that was a different type.