The oliebollen is something that KLM could give to all pax. (and also try to persuade naive pax. that dutch cuisine is excellent) but i guess maybe it might not be deemed sustainable. Aegean (in Greece) follows the tradition of the country and on all(i think at least) flights on 31st gives a pomengranate (to smash on a door) and on the 1st they give "vasilopita" (new year's pie)