The particular joy of a parfait, which is that much heavier and more luxurious than other ice creams, is that you don't have to dust off the ice-cream maker.

200g caster sugar
1 vanilla pod, slit
9 medium organic egg yolks
450ml double cream
85ml armagnac
285g chestnut purée
icing sugar
vanilla essence
6 marrons glacés

Merchant Gourmet does a fine job of keeping the country supplied with unsweetened chestnut purée at this time of year. It's available in major supermarkets at around £1.39 for 435g.

Place the sugar and vanilla pod in a small saucepan with 300ml water. Bring mixture to the boil and simmer until visibly thicker.

Place the egg yolks in the bowl of a food processor and trickle in the hot syrup very slowly, with the processor on a high speed. The mixture should swell to a thick, pale cream. Continue to whisk until it is cool. Whisk the cream with the armagnac in a bowl until it forms soft peaks, without being stiff.

Combine the two mixtures and pour into six plastic cups. Cover each one and freeze them overnight. Sweeten the chestnut purée to taste with the icing sugar and add a few drops of vanilla essence. Unmould the ice cream, place a marron glacé on top of each one, and serve it with a scoop of the chestnut purée.