So, in the end, it is better get them from the super market!
Blanched Chestnut 3 minutes in boil water and remove the skin
Syrup : 500ml water ; 150g sugar ; Bring water and sugar to boil, add the marron cook for 20 minutes over low heat.
Take off the heat, cover and let sit for 24 hours
After 24 hours make new syrup : 500ml water; 375g sugars; 1 vanilla bean
Bring together to boil, add the marron for 20 minute, off the heat, cover, and let sit for 24 hour
Use the same syrup add 175g of sugar
Same process for 24 hours
After that drain for 2 hour
Make flat icing (icing and left over syrup)
To Glace the marron