Take the chestnuts and use the tip of a small sharp knife to score a cross into the skin on the flat side.
Then place them (scored side uppermost) on a baking tray and roast them for 25 minutes.
When they are ready the cross will have peeled open slightly exposing the flesh of the chestnut.
Now using a cloth to protect your hands gently squeeze one of the chestnuts and then peel away the shell and any brown skin and repeat until that are all peeled. (If they start to get cold and become tricky to peel, pop them back in the oven for a few minutes.
Leave the peeled chestnuts to cool and store in a lidded container in the fridge, ready to sauté on Christmas day.