For the curd: Halve the passion fruits and scoop the flesh, pulp, seeds and juice into a food processor and blitz for a minute to release the seeds. Then pass through a sieve and discard the seeds.
In a separate bowl, whisk together the eggs, egg yolks and sugar. Then, in a medium pan melt the butter over a low heat. Once melted, stir in the egg/sugar mixture and the sieved passion fruit juice. Continuously stir until thickened, and then take off the heat to cool.
For the pastry: Mix the flour, caster sugar and salt together in a large bowl. Add the diced butter, rubbing in with your hands until it resembles breadcrumbs. Add the water a little at a time, until it forms a rough dough – you may not need all the water. Turn it out onto a lightly floured worksurface and knead until it comes together to form a uniform dough. Flatten into a disc, wrap in clingfilm and put into the fridge for 30 minutes.
Once chilled, roll the pastry out onto a lightly floured worksurface and roll into a large circle about 2-3mm thick. Carefully line your tart ring or tin, and prick the base all over with a fork. Then put back in the fridge for 30 minutes, and preheat the oven to 180C/160C Fan/Gas Mark 4.
Once the pastry is firm, line with baking paper and fill with baking beans. Bake for 20 minutes, then remove the baking beans and baking paper and bake for another 5 minutes until the pastry on the base of the tart is dry. Leave the tart to cool completely.
Once the tart is cool, spread the curd evenly over the tart and then put into the fridge for at least 30 minutes to set. At this point, you could leave this in the fridge overnight.
For the meringue: Whisk together the egg whites and sugar in a large bowl and place over a pan of simmering water. Making sure the base of the bowl isn’t touching the water. Whisk very often to ensure the eggs don't cook, and keep over the heat until the mixture reaches 60C on a sugar thermometer. Then remove from the heat and using an electric whisk, whisk until you reach stiff peaks and the outside of bowl feels lukewarm. This will take 10 minutes or so. Finally, place the meringue into a piping bag fitted with a star nozzle and pipe over the tart.
Best served on the day of baking, but can be kept in the fridge for 2 days in an air-tight container.