happy new year to you too, mel.
actually, someone had just given me a box, which is why i didn't bother making marzipan. i think i like it better than using the traditional marzipan.
if for some reason you need or want to make them, making the marzipan is much faster. grind the blanched almonds. bring about an equal amount of sugar (don't quote me on the ratio;look it up) with some water to the softball stage. knead the almond mass and sugar together. probably around an hour's work.
to candy chestnuts, cook in a simple syrup (maybe with a little vanilla bean) until the chestnuts are soft. let them cool in the syrup and sit for a day or two. after that, you repeat the following process: take out the chestnuts and reduce the syrup by cooking maybe 5 or 10 minutes. return the chestnuts and let sit another day or two. i think this would be repeated until the sugar gets to about the soft ball stage.
if i were to try a lazier approach, i might cook the chestnuts in the syrup until soft, remove them, bring the sugar to a bit less than the softball stage, return the chestnuts, and just let them sit for a couple of weeks. if you're into home canning, putting them up in a very heavy syrup and letting them sit for a couple of months might give you a nice product, too.
thinking about it, i bet you could just try making a chestnut marzipan, just substituting the chestnuts for the almonds. i might even give this a try sometime.