Cut a slit in the chestnut skins, especially if fresh, and scorch over an open fire using a specially made pan with holes on its bottom. Peel the chestnuts. Boil in equal measures of water and milk flavoured with a vanilla pod. Rub through a sieve. For every 600 g of chestnuts add 400 g of sugar, 50 g of alchermes, 80 g of rum and vanilla flavouring to taste. Mix well. In a separate bowl beat 4 eggs and then add to the chestnut mixture together with 0.3 litre of milk. Prepare some pastry with white flour, egg, sugar and a little butter. Roll out very finely and line a pie dish with it. Add the chestnut filling and bake in a very low oven (120° C) for 2-3 hours.