Taken from Bread, Cake, Doughnut, Pudding (£25; Penguin Books)
- For the pastry
- 250g strong white bread flour, plus extra for dusting
- a pinch of fine sea salt
- 1 egg, beaten
- 50g warm melted unsalted butter
- 100ml warm water
- 1 egg, beaten, to glaze
- For the filling
- 4 large potatoes, cooked in their skins, peeled
- 200g Brie (or you can use a truffle Brie, but in that case leave out the black truffles)
- Fine sea salt and black pepper
- 2 or 3 small black truffles
- 4 teaspoons truffle oil
Put the flour and salt into the bowl of an electric mixer with a beater attachment, then add the beaten egg and warm melted butter and mix together. Slowly add the warm water and mix until you have a soft pliable dough. Cover the bowl with clingfilm and leave in a warm place to rest for 25 minutes.
Preheat the oven to 180°C/fan 160°C/gas 4. Grease an 18cm cake tin 5cm deep, with a removable base, and line the base with baking paper.
Cut off one-third of the pastry and set aside to make the lid.
Roll out the rest of the pastry into a circle about 28–30cm across and about 2mm thick and line the prepared cake tin, leaving 1cm overhanging.
Slice the potatoes and Brie 0.5cm thick. Put a layer of sliced potatoes in the bottom of the tin and add some seasoning. Follow with a layer of sliced Brie, then some slices of truffle and a dash of truffle oil. Repeat the layers until you reach the top of the tin.
Roll out the pastry for the lid, place it on top, and trim it so it fits and covers the filling. Eggwash, then fold the overhanging pastry over the lid and seal.
Put it into the fridge to rest for 10 minutes, then place on a baking tray and bake for 30–35 minutes, until golden brown.
Serve with pickled tomatoes.