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.