I assume you mean for inter-continental premium cabin service.

BA has a "raid the larder" feature for Club World but the cabin crew don't really let you know it's there the two times I've flown that. I've heard it's packaged cheese and crackers/biscuits and fruit, and maybe sandwiches. Never heard if it is available on Qantas or AA. If so, I've never seen it offered.

US has a mid flight snack of ice cream (Hagen-Daz IIRC) coming back from Europe that is distributed.

CP has snacks placed somewhere in the cabin which is usually fruit and various packaged snacks for trips not to or from Asia. The flights to/from Asia have snacks with the Asian market in mind such as noodles (gett he crew to add hot water), sea weed (yum!), etc.

CX does (or did in 1984) have a small snack for economy passengers but only if you ask.