I can see you are quite the connoisseur d'hote cuisine there RKay, now arn't you. ;-) In all honesty though, I think British food gets a bad rap.

Back to 'gobsmacked' ..I have heard 'gobstruck' said too. But this is a whole word cluster... or whatever they're called... because there's the 'gift of the gab' and there's 'gabby'.. then there's 'gobby', and then there's 'a gobbin' (from 'a gobbin idiot' I think), ......etc.
English slang is such a laugh. I have the feeling that these composite (compound?) words are quite prominant in Brit slang... I can think of a handful which I'd really rather not mention right now. Particularly the noun/past-tense verb combination. I guess it's an easy means of words formation at anyone's disposal.