Australia doesn't have much in the way of great food at theme parks, so I couldn't really choose one. However....
For the Grandest food I ever ate, that would have to be Victoria & Albert's Restaurant at WDW.
I'm strangely addicted to Monte Cristo Sandwiches at Blue Bayou in DL too
Also - My favourite Multiple Repeat treat is the Gyoza Sausage Buns and the Sea Salt Ice-cream at Tokyo Disneyland - these are a MUST HAVE !
Cheers,
Rob.