I feel like I'm the last fairly serious home cook to learn this, but I finally roasted my first batch of fresh chestnuts. Saraga had a huge bin ($3.99 a pound) and I figured it was about time I learned the drill.
Start with a half-pound or so of fresh chestnuts. Using a sharp paring knife, score the outside of each nut with an "X". Put the chestnuts on a baking sheet, and roast in the oven at 425 for 15-20 minutes or until the nuts are soft and the shell has started to peel back.
Peel while they're warm (it's easier.) Store the nut meats in an airtight container in the refrigerator.
Now, what to do with all these chestnuts. (They're good to eat on their own, but they beg to go in soup, stuffing, or mmm, something with butternut squash.)