Start with the pastry. Put the flour in a large bowl or food processor, add the butter and rub or pulse in until it’s well distributed. Mix in the salt and sugar, then the beaten egg, and bring the mix together into a ball (it should be soft, but add a little more flour if it’s sticky). Flatten, wrap and chill for at least an hour.

Take out of the fridge 10 minutes before rolling out.

Meanwhile, put the cream and milk in a medium pan on a medium-low heat. If using the vanilla pod, slit it lengthways, then scrape out the seeds into the liquid. Add the pod, too, and bring the milk mixture to just below a simmer.

While it’s heating up, put the eggs and yolks (set the extra white aside for now) in a large heatproof bowl with the sugar and cornflour, and vanilla extract, if using. Whisk until well combined, then pour the hot liquid on to the egg mix, whisking all the time. Pour back into the pan and heat, still whisking, until the custard thickens, then take off the heat and leave to cool.

Trim the rhubarb, then cut it into 2cm pieces. Wash well then arrange, still wet, in a single layer in a baking dish. Scatter over the orange zest and juice, then sprinkle over the sugar.

Roll out the pastry on a lightly floured surface to about ½cm thick, then fold it in on itself and place in a 20cm wide, loose-based tart tin. Unfold the pastry, making sure it’s square to the sides of the tin, leaving any excess overhanging the sides, then put in the fridge for 20 minutes.

Heat the oven, and a baking tray near the top, to 200C (180C fan)/390F/gas 6 and put the rhubarb in the oven for 15-20 minutes, until tender, but still holding its shape.

Trim away the pastry’s overhanging edges, then line it with baking paper and baking beans/dried beans or raw rice, making sure they come right up the sides to support the pastry. Put on the hot tray and bake for 15 minutes, until lightly golden on top. Lift out the paper and beans, then bake for another five minutes to brown the base.

Whisk the reserved egg white to loosen, brush a little over the base of the tart, then return it to the oven for two minutes to seal. Turn down the oven 150C (130C fan)/300F/gas 2.

Pour the custard into the case, removing the vanilla pod first, if necessary, then bake for 30-40 minutes, until set on top but still a little wobbly in the middle – be careful not to overcook it. Remove and set aside to cool.

Once the rhubarb and the tart are completely cool, arrange the rhubarb in concentric circles on top, shaking off any syrup before doing so. Use the excess syrup to brush the top of the rhubarb, then slice and serve.