Cut the vanilla pod in half lengthways, scrape out the seeds and put them in a small saucepan with the cream. Discard the pod. Gently bring the cream to a simmer — do not boil — then remove from the heat.

Heat the oven to 160°C/gas 3.

In a bowl, beat together the egg yolks and caster sugar until light and fluffy. Stir in the warmed cream and mix well.

Make a bain-marie. Place the mixing bowl over a saucepan of simmering water on a gentle heat, stirring constantly until the mixture coats the back of the spoon: about 8 minutes.

Pour the custard into individual ramekins (or you could use one large ovenproof serving dish).

Make a bain-marie with a deep roasting tin: place the dishes in the tin and half-fill the tin with hot water. Place it in the oven and cook the custards for 20 minutes. Remove and allow to cool, then place in the fridge overnight.

The next day, heat the grill to high. Sieve the icing sugar over the custards and place under the grill. The sugar will melt and caramelize. Move the dishes around so that they brown evenly. Leave to cool completely before serving.