Cooking chestnuts

[furtech]

One of my favorite fall dishes is "kuri gohan," or chestnut rice. The "recipe" is ridiculously simple (essentially cook chestnuts with rice; my problem is cooking the chestnuts. I did what one cookbook said: pour boiling water over them, then bring slowly to a boil again. Trouble is, that merely seemed to parboil them. While the skin came off easily enough, the nuts are hard and crunchy and not soft/mushy. How long are you supposed to boil/cook them??

Now that these chestnuts are peeled but undercooked, what's the best way to get them soft and edible? Microwave them with a little water? For how long?

Experienced suggestions welcome!