First make the custard. Place the milk, cream, vanilla pod and seed into a thick-bottomed pan and place on a high heat until boiling. Meanwhile add the sugar to the yolks and beat immediately.
Next, beat the egg yolks until they are thickened and pale. Slowly pour half the hot mix onto the bowl of beaten eggs, whisking continually. Take the pan off the heat. Use a heatproof spatula to scrape the egg and milk mix from the bowl back into the pan. Place back on a medium heat and stir with a spatula. Stir in a figure of eight to prevent hot spots forming.
The mixture should begin to thicken within about 2 minutes. The perfect temperature is 82°C, and a thermoprobe thermometer is useful here. If you don’t have a probe, watch for little puffs of steam escaping from the side of the pan. These are a warning sign that the custard is getting too hot; take the pan off the heat and continue stirring.
When the mix has thickened enough to coat the back of the spatula, take off the heat and strain immediately through a fine sieve to remove any small lumps, which may have formed. Leave to cool before using the trifle.
While the custard is cooling, make the jelly. Bring the juice, water, cordial, wine and sugar to the boil before adding the blackberries. Boil for 2-3 minutes to extract the juice, turning the liquor slightly purple. Strain, removing the blackberries, then add the soaked gelatine and stir well until dissolved. Leave to cook slightly. Now cube the sponge into 1cm pieces and sprinkle onto the base of the trifle dishes (either 4 separate dishes or one large one), pour over the sherry and leave to absorb.
Place some fruit in each dish on top of the sponge. Pour over the cooled jelly and refrigerate until set (about 2 hours). When the jelly is set, pour over the thickened, cooled custard. At this point it’s best to leave the trifles covered in the fridge overnight, but leave for a couple of hours at least.
For the Chantilly cream, soft whip the double cream with the icing sugar (don’t over whip it), and pipe or spoon it over the set custard. Finally, sprinkle over a few hundreds and thousands and serve.