This coincides with Girona Fiestas (Fires de Sant Narcis - the week or 10 days around the 29th October). The Castanyada (chestnut eating) is celebrated in Catalonia mainly on All Saints' Day. In Occitania, the similar festival Castanhada is celebrated, but not on All Saints' Day as in Catalonia. Like Halloween or the Celtic Samhain, its origins are in an ancient ritual festival of the dead.
In Catalonia it consists of a meal of chestnuts, 'panellets' (sweets made from marzipan and pine nuts), sweet potato and preserved fruits, typically with moscatell to drink. It seems that the tradition of eating these foods comes from the fact that during All Saints' night, the night before All Souls' Day in the Christian tradition, bell ringers would ring bells in commemoration of the dead into the early morning. The festival is usually depicted with the figure of a castanyera: an old lady, dressed in peasant's clothing and wearing a headscarf, sat behind a table, roasting chestnuts for street sale. 
castañas - chestnuts