Start by cross scoring and roasting the chestnuts using this method. Let the nuts cool, then peel the shell and inner membrane.Roast and then peel the chestnuts.In a heavy pot, add the water and sugar, then bring the mixture to a boil, stirring to dissolve the sugar. Add the chestnuts and reduce the heat to a simmer. Add the bourbon or vanilla extract and the salt. Stir well. Cover the pot and simmer the chestnuts for 2 hours.Simmer the chestnuts in the sugar water mixture.Leave the pot covered and remove it from the heat. Let the chestnuts sit for 24 hours. The finished nuts should hold their shape, but be soft to the touch.After simmering for 2 hours and resting in the syrup for another 24, the nuts will be soft but still hold their shape.Serve them individually with a good cup of coffee, or spoon a few, along with a bit of the syrup, over ice cream.