Duke of Cambridge tart

Method

1. Pulse the flour and butter in a food processor until it resembles fine breadcrumbs. Add the beaten egg and 1 tsp cold water, then pulse again to a smooth dough – try not to overmix or the pastry will be tough. (Or make the pastry by hand: put the flour and butter in a large bowl, rub to fine crumbs with your fingertips, then mix in the egg and water using a round-bladed knife.) Wrap well, then chill for at least 1 hour or overnight (see tips).
2. Heat the oven to 200°C/180°C fan/gas 6. Roll out the chilled pastry on a dusted work surface to 3-4mm thick, then use to line the prepared tart tin. Chill in the fridge for at least 20 minutes (see Make Ahead).
3. Line the chilled pastry with baking paper, fill with the ceramic baking beans or uncooked rice, then bake for 15 minutes. Remove the baking beans/rice and paper and return the tart case to the oven for 10 minutes, then remove, trim the edges and set aside. Turn down the oven to 140°C/120°C fan/gas 1.
4. Meanwhile, make the filling. Put both sugars in a large mixing bowl and rub with your fingertips to remove any lumps. Add a pinch of salt, the egg yolks and custard powder, then gently mix with a wooden spoon until combined.
5. Put the butter, cream and vanilla in a large saucepan over a high heat and bring to the boil. Remove from the heat and set aside to cool for a few minutes. While still hot, pour in the sugar/egg yolk mixture and stir. Pass through a sieve set over a large jug to remove any lumps.
6. Spread the marmalade over the base of the pastry case, then sprinkle with the chopped candied peel. Pour in the filling mixture, transfer to the oven and bake for 1 hour until set but with a slight wobble. The filling will rise up, but as the tart cools it will sink back down. Leave to cool, then chill in the fridge for at least 1 hour before slicing (see tips). Serve with clotted or double cream.