The custard mix will make more than four spring rolls, so I suggest you freeze the extras for another time. If you can get hold of the red dessert gooseberries, it will give a good splash of colour.
300ml single cream
5 egg yolks
60g caster sugar
8 or so spring roll wrappers
1 small egg, beaten
100ml elderflower cordial
150-200g gooseberries (green or red)
Vegetable or corn oil for deep frying
Icing sugar for dusting
First, make the custard: split the vanilla pod in half lengthways and scrape out the seeds. Put the cream, vanilla pod and seeds into a small saucepan and bring to the boil. Remove from the heat and leave to infuse for about 10 minutes.
In a bowl, mix the egg yolks, sugar and cornflour. Remove the vanilla pod from the cream and pour on to the egg mixture and mix well with a whisk. Return to the pan and cook gently over a low heat for a few minutes, stirring constantly with a wooden spoon until the custard thickens; don't let it boil.
Remove from the heat and give a final mix with a whisk and transfer to a clean bowl. Refrigerate for an hour or so.
Meanwhile, put the elderflower cordial in a pan and bring to a simmer, stir in the gooseberries, cover with a lid and remove from the heat. Stir every so often so they gently cook and keep their shape.
To prepare the spring rolls, transfer the custard to a piping bag with the widest tube. Lay the spring roll wrappers on a work surface with a corner facing you. Pipe the mix along the centre of each one, stopping short of the left and right corners. Fold the corners towards the middle, brush the pastry with the beaten egg and carefully roll into cylinders.
Preheat about 8cm of oil to 160-180C in a large, thick-bottomed saucepan or electric deep-fat fryer. Deep fry the spring rolls for a minute or so until golden, turning them with a slotted spoon while they are cooking, then drain on some kitchen paper.
To serve, dust the spring rolls with icing sugar, spoon the gooseberries and syrup in to serving bowls and place the spring rolls on top.