Method

1. Up to 36 hours ahead - put the split vanilla pod and cream in a heavy saucepan and gently bring to simmering point. Whisk as soon as the first bubbles start to rise, then remove the pan from the heat and leave to infuse for about 20 minutes.

2. Fish out a half-pod from the cream and hold it over the pan, then use the tip of a small knife to scrape the black seeds inside into the pan. Repeat with the other pod, then whisk to disperse the seeds.

3. Meanwhile,whizz the egg yolks and sugar in a food processor for 2-3 minutes until thick and creamy. Scrape the mixture into the cream and stir to combine. Place the pan over a medium heat and gently whisk constantly until the custard has thickened considerably and is on the point of boiling (when the first few bubbles break through the surface).

4. Immediately remove the pan from the heat and plunge the base into a sink of ice-cold water. Continue to gently whisk for 1-2 minutes, or until most of the heat has dissipated. Leave to cool, whisking occasionally to prevent a skin forming.

5. Meanwhile, place six little heatproof dishes, about 10cm in diameter and 2.5cm deep (see tip), on a tray that will fit in the fridge. Divide the blackberries among them, then cover with the cool custard and chill until firmly set. Loosely drape with cling film over to cover.

6. An hour or so before serving - if you don’t have a blow torch to brûlée the custard, use a very hot grill. Sprinkle a thin, even layer of sugar over each dish then, if using a blow torch, carefully ‘burn’ the sugar, starting on the nearest side: the sugar will bubble and turn a dark caramel. Wait for a few minutes for the surface to harden before serving but DO NOT be tempted to touch as the sugar remains blisteringly hot for some while. Alternatively, put the ramekins on a baking sheet close to the grill until the sugar caramelises. Keep them cool until ready to serve, but not in the fridge or the caramel will soften.