Rhubarb and custard Portuguese tarts

Method

1. Dust a work surface with flour. Fold the pastry in half then roll out into a rectangle about 3mm thick. Roll up lengthways, sealing the edge with a little water, to create a long, spiralled log. Slice into 1-1.5cm discs then, using a rolling pin, roll each one flat into a circle around 2mm thick. Grease the holes of your tin with a little butter then line each hole with the pastry discs and put in the fridge.
2. Put the milk in a small pan with the cinnamon stick and vanilla bean paste, bring to the boil then remove from the heat and discard the cinnamon. Put the flour in a bowl and whisk in a little of the milk bit by bit – you must go slowly to avoid lumps. Transfer the mixture back to the pan and put over the heat for 2 minutes or until thickened, whisking continuously. Set aside.
3. Heat the oven to 160ºC fan/gas mark 4. Put the rhubarb, sugar and water in a saucepan and simmer for 10 minutes. Transfer to a blender and whizz until smooth, then stir it into the thickened milk mixture. Whisk the egg yolks in a bowl, then whisk them into the milk. Transfer to a jug.
4. Remove the pastry cases from the fridge and pour the rhubarb custard into each one, about three-quarters of the way up. Cook in the oven for 10 minutes, then remove and finish off under a hot grill until just starting to caramelise and blacken. Leave to cool before eating.