Lembas

Warning: Wikipedia contains spoilers

In J. R. R. Tolkien's fictional world, Middle-earth, lembas, also called waybread in the Common Speech, is a special food made by the Elves (Middle-earth). The cakes are very nutritious, stay fresh for months when wrapped in leaves, and are used for sustenance on long journeys. Lembas is a brownish colour on the outside and a cream colour on the inside. The secret of lembas is closely guarded, and only on rare occasions is it given to non-Elves. Like other products of the Elves, it is offensive to evil creatures; Gollum refuses outright to eat of it.

Galadriel gives a large store of it to the Fellowship of the Ring upon its departure from Lothlórien. Frodo Baggins and Samwise Gamgee subsist on it through the majority of their journey from there into Mordor.