Christmas Cooking - Chestnuts

We tried something we have never done before. The very last thing we did on Christmas Eve was roast chestnuts in the oven. So I dutifully put x's on about 25 chestnuts that I bought at the grocery store. Probably not the best place to source chestnuts, but I don't know
where else to get them in our neck of the woods.
I carefully laid them all with the x up on the baking sheet and slide them into a 425 degree oven for the estimate time of 25 minutes.

What's left of a chestnut

We are sitting around enjoying snacks and drinks as the chestnuts roast - that is until the first one exploded. It looked like sawdust inside the oven - thank goodness for an self-cleaning oven.

Is this what they are supposed to look like?

So, figuring they were probably done now, I took them out of the oven and left them on the stove top to cool a little before we made an attempt at peeling them. We all gathered around to look at them and test the temperature by trying to pick them up (unwise at this stage of the game), when the next one exploded all across the kitchen. Needless to say, I quickly covered the rest with a dish towel. I thing we give it an A for excitement. I, personally, didn't care for them. That said, I may have had bad ones and not known it,  but I assume that they are an acquired taste, like boiled peanuts - you either like them or you don't there's no in between.