For the chestnut jam, bring water (1) to a boil, add the chestnuts and simmer on low heat for 20 minutes.
Drain the water and strain the chestnuts. Add honey, vanilla pulp and water (2), stir well and leave in a cool place for 24 hours.
The following day, heat the chestnut puree in a saucepan and cook, stirring, until bubbling, 20 min.
Pour the chestnut jam into small jars rinsed with hot water and store in a cool place.