For the pastry, use a food processor (or mixing bowl and wooden spoon, if you’re feeling energetic) to cream the butter and sugar together.
Score the vanilla pod lengthways and scrape in the seeds. Grate in the orange zest, pulse in the flour, egg yolks and a pinch of salt, then add little splashes of milk until it forms a ball. Wrap in clingfilm and chill for an hour.
Roll out the pastry on a floured surface to line a greased, loose-bottomed 27cm-diameter, 2.5cm-deep tart tin. Push the pastry into the sides, prick with a fork, line with 4 pieces of clingfilm, then fill with rice or dried beans. Chill the tart case for 1 to 2 hours.
Meanwhile, preheat the oven to 180°C/350°F/gas 4. Bake the tart case (clingfilm and rice in place) for 10 minutes, then remove the clingfilm and rice, and cook for another 5 minutes. Remove and turn the oven down to 170°C/325°F/gas 3.
Melt the chocolate in a bowl over a pan of simmering water.
Smash the cardamom pods and heat the milk, cream and cardamom in a pan, then remove from the heat and infuse for 10 minutes.
Beat the sugar and egg yolk with a pinch of salt, then stir into chocolate. Stirring all the while, add the milk by straining it through a sieve, discarding the cardamom.
Pour the chocolate mixture into the tart case and scatter over the raspberries. Bake for about 25 minutes – the tart should still be wobbly in the middle.
Remove from the oven, leave to cool, then chill in the fridge before dusting with icing sugar and serving with crème fraîche, or simply with more berries.