To make the pastry, place the flour, butter and sugar in a food processor and process until the mixture resembles fine breadcrumbs. While the motor is running, add the egg yolks and rum, and process until the dough just comes together.
Gently bring the dough together to form a ball, wrap in cling film and refrigerate for half an hour.
Preheat oven to 160°C. Roll out the pastry and line a 22cm loose-bottomed fluted tart tin. Trim the edges and prick the base with a fork. Refrigerate for a further 30 minutes.
Line the pastry case with non-stick baking paper and fill with baking beans. Place in the oven and cook for 20 minutes, then remove the paper and beans, and cook for a further 10–12 minutes or until the pastry is light golden. Allow to cool slightly in the tin.
Reduce oven to 140°C. Place the cream, eggs, egg yolks, sugar and lemon juice, rum and passionfruit juice in a bowl and whisk to combine. Strain the mixture into a clean bowl and then carefully pour the passionfruit filling into the tart shell. Cook for 30 minutes or until just set, then allow to cool to room temperature before refrigerating until cold. The tart will keep in the fridge at this point for 1 day.
Just before serving, sprinkle over the granulated sugar and blowtorch to caramelise the sugar. Leave to cool and then break with the back on a spoon.