(Land of). An imaginary land of idleness and luxury. The subject of a burlesque, probably “the earliest specimen of English poetry which we possess.” London is generally so called, but Boileau applies the phrase to Paris. (See page 270, col. 2, Cockney )
Allied to the German, kuchen, a cake. Scotland is called the “land of cakes” there is the old French word cocaigne, abundance. Compare Latin coquo, to cook, coquinaria, coquina, etc.
Ellis, in his Specimens of Early English Poets (i. 83-95), has printed at length an old French poem called “The Land of Cockaign” (thirteenth century) where “the houses were made of barley sugar and cakes, the streets were paved with pastry, and the shops supplied goods for nothing.”
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894