First, make the custard. Pour the milk into a small saucepan and add the vanilla. Set over a medium heat and bring to a gentle simmer, around 4-5 mins. Meanwhile, whisk together the sugar, cornflour, egg yolks and a pinch salt in a large bowl until smooth and pale. Slowly pour the hot milk into the egg yolks, just a splash at a time, whisking well after each addition. Return the mixture to the saucepan and set over a medium heat. Cook, stirring frequently, for 8-12 mins until it thickens and coats the back of a wooden spoon. Transfer to a container and leave to cool, then leave to thicken in the fridge overnight. Will keep chilled for two days.

Heat the oven to 150C/130C fan/gas 2. To make the meringue, tip the egg whites and cream of tartar into the bowl of a stand mixer fitted with the whisk attachment. Whisk on medium speed for 3-5 mins until you have soft peaks.

With the mixer speed still on medium, add the sugar 1 tbsp at a time. Increase the speed and whisk for 12-15 mins until the meringue is stiff and glossy. Mix the vinegar, cornflour and vanilla in a cup until smooth, then whisk the mixture into the meringue until fully incorporated, around 1-2 mins.

Spoon the meringue onto a baking sheet lined with baking parchment, creating a high mound, then smooth into a high dome 23cm wide and flatten the top. Bake the meringue for 10 mins, then lower the temperature to 140C/120C fan/gas 1 and bake for a further 1 hr 30 mins. Turn off the oven and leave the meringue in the oven overnight, with the oven door closed.

To poach the rhubarb, put it in a saucepan with the sugar, vanilla, orange zest and 125ml water. Set over a medium heat, until the sugar has dissolved, around 1-2 mins. Once dissolved, cook for 4-5 mins, then remove from the heat and cover with a lid for 5 mins. Use a slotted spoon to remove the rhubarb and transfer to a heatproof container. Then, boil down the liquid for 5 mins until it turns into a more concentrated syrup and pour over the rhubarb. Store in the fridge, ideally overnight until ready to serve.

When ready to serve, whisk the double cream until thickened and holding its shape. Whisk in the cold custard and spoon over the top of the meringue. Scatter over the poached rhubarb and drizzle over the syrup. Serve straightaway.