Put the rhubarb in a pan with the sugar and chopped ginger. Cook over a low heat for 10 mins or until the rhubarb has softened and begun to break down. Mix a little of the rhubarb juice with the cornflour in a small bowl, then pour into the pan and stir until thickened. Pour into the base of a round roughly 20cm dish. Leave to cool completely.

For the custard, pour the double cream, sugar and vanilla pod (as well as the scraped-out seeds) into a pan and bring to a simmer. Scoop out the pod and discard. Whisk the eggs in a bowl and gradually pour over the simmering cream, whisking continuously. Pour the mixture back into the pan. Cook over a low heat, continuously stirring, for around 10 mins until it reaches 86C on a cooking thermometer, or is thickened. Pour over the cooled rhubarb, smooth to an even layer and chill overnight.

Sprinkle the demerara sugar over the top and caramelise using a blowtorch until deep golden brown. Serve.