Plajia cakes were a variety of cake, a type of food that originated with the Aunithox civilization.
Starfleet Captain Morgan Bateson preferred fresh-made plajia cakes, and didn't find "week-old" cakes palatable.
By the 2360s, Counselor Bailey was not familiar with this food as the Aunithox had been destroyed by a 2330s supernova. (TNG - Special comic: "Out of Time")