Castagnas de Carlos Almeda Rinse 1,5 kg fresh chestnuts. Incise them with a sharp knife and put them in a pan of cold water with some salt and a broken stick of cinnamon. Bring everything to the boil and simmer for 10 to 12 minutes till the chestnuts are soft inside. Traditionally chestnuts are eaten on the 11th of November, the day of S. Martinho.