Tranche Napolitaine is a French dessert. It is a cake made of Neapolitan Ice Cream and mousse. The layered ice cream is placed on top the mousse. It is served in slices.
In France, most people expect the Neapolitan ice cream layers to be red (strawberry), white (vanilla), and green (pistachio.)
The dessert is not called Napolitain on account of any association with Napoleon, but rather because it was made in the “style” of desserts from Naples, which were often layers of different colours, textures and tastes.
Literature & Lore
The term “tranche napolitaine” is also applied now to train engines which are painted different colours in sections with an underlying colour at the base acting as the foundation colour, as in the base of the Neapolitan Slice. It is also applied to a layered sky.
Nowadays, in North America, the phrase “Neapolitan Slice” mostly refers to a slice of what is reputedly Neapolitan-style pizza.