Dauphinois potato and leek pie

Method

1. Heat the oven to 160ºC fan/gas 4. For the pastry, put the flour in a large mixing bowl with a pinch of salt, add the butter and rub into the flour using your fingertips until the mixture resembles breadcrumbs. Stir in the cheddar, then quickly stir in the egg and just enough of the water so the dough starts to come together in chunks – it shouldn’t be sticky. (To make this in a food processor, whizz the butter and flour, then pulse in the cheddar, followed by the egg and water.) Tip out the dough onto a lightly floured surface and bring together into a ball. Flatten, then wrap and rest in the fridge.
2. Bring a large pot of water to the boil, then add the potatoes and cook for 5 minutes. Drain well, then leave to cool.
3. In a small pan, warm the cream with the garlic, thyme/rosemary, bay leaves, a large pinch of salt and freshly ground black pepper. Set aside to infuse.
4. Heat the butter in a large frying pan over a low-medium heat until melted and foaming, then add the leeks. Cover and cook for 10-15 minutes, stirring now and then, until softened. Add the wine and simmer for 2-3 minutes or until mostly evaporated. Stir in the flour, then add the stock and simmer, stirring, until thickened.
5. On a lightly floured surface, thinly roll out two thirds of the pastry and press into the base and sides of a 20cm springform cake tin, allowing a little to hang over the edge.
6. Put a baking sheet into the oven to heat up. Mix the potatoes, leeks, cream and grated cheese. Taste and add more salt and black pepper if needed (it should be well seasoned). Layer half the potato mixture in the pastry case, add the brie/camembert in a layer, then top with the remaining potato mixture. Roll out the rest of the pastry into a disc and make a hole in the middle for steam to escape. Lay the pastry on top of the pie, pinching the edges together to seal and crimp. Brush the top with the milk.
7. Put the pie on the hot baking sheet and bake for 60 minutes until golden and bubbling. Rest for 10 minutes before unclipping the sides of the tin. Slice and serve.