Gianduja or gianduia is a sweet chocolate spread containing about 30 % hazelnut paste, invented in Turin during Napoléon's regency (1796–1814). The Continental System - imposed by Napoleon in 1806 - prevented British goods from entering European harbours under French control and put a strain on cocoa supplies. A chocolatier in Turin named Michele Prochet extended the little chocolate he had by mixing it with hazelnuts from the Langhe hills south of Turin. Based on Gianduia, Turin-based chocolate manufacturer Caffarel invented Gianduiotto in 1852.
It takes its name from Gianduja, a Carnival and marionette character who represents the archetypal Piedmontese, a native of the Italian region where hazelnut confectionery is common.