Clutton says: “This is a tall, standing-proud pie made with hot water pastry, which is not only delicious but so easy to work with. Forget everything you know about keeping things cool to work with pastry – the onus here is on working with this pastry while it is still hot. Or at least warm.

“Classic hot water pastry, like Paul Hartland of Mrs King’s Pork Pies makes for his pork pies, contains lard. This is in part for the connection between the meat and the fat of the same animal, but also for the remarkable flavour and texture the lard gives. The recipe here has measurements for using butter or lard. The measurements are different as butter contains more water. The meat-free filling is deeply flavoursome, given a double-umami lift from fresh wild mushrooms and dried porcini. It can be made a day ahead of baking the pie and chilled until needed.”

Serves 6-8

Ingredients

25g dried porcini
250ml boiling water
1 small celeriac (about 650g)
800g potatoes
2 onions
60g butter
1 tablespoon olive oil or rapeseed oil
1 sprig of rosemary
80g mixed mushrooms of your choosing
1 apple
250g creme fraiche
80g gruyère

For the pastry:

350g plain flour, plus extra for dusting 250g strong white flour
2 teaspoons fine salt
220g butter (or 200g lard)
1 egg

You will need a deep 22cm springform cake tin.

Method

Sit the dried porcini in a heatproof bowl and cover with the boiling water. Set aside.

Cut off the gnarly top and bottom of your celeriac. Peel, halve and cut it into slices about 1cm thick. Put the celeriac slices in a saucepan of boiling salted water and cook for 15–20 minutes until just tender. Peel the potatoes, cut into slices about 1.5cm thick and simmer in a separate pan of boiling salted water until tender. Drain the vegetables when ready and set aside, seasoning them while they’re still warm.

Peel and finely chop the onions. Heat the butter and oil in a large saucepan over a medium heat, then add the onions and cook until just softening. Chop the rosemary leaves and add those too. When the onions are soft, add the mushrooms, roughly chopping them if large. Lift the now-rehydrated porcini out of the water (keep the water), roughly chop them, and add to the pan too. Cook for 5 minutes, then pour in the porcini soaking water. Mix and remove from the heat.

Peel, quarter and core the apple, dice, then add to the pan of mushrooms. Now cut the cooked celeriac and potato slices into roughly 1cm cubes (you don’t need to be too precise about it), add to the onion/mushroom pan, stir in the creme fraiche and season generously with salt and freshly ground pepper. Your filling is now almost ready – carry straight on or keep it in the fridge for up to a day, making sure you return the filling to room temperature before building your pie.

To build your pie:

Grate the gruyère and keep back for adding to the filling.

Preheat the oven to 170C fan/190C/375F/gas mark 5 with a large baking tray inside to get hot. Use just a little of the butter (or lard) to grease the base and sides of your tin.

To make the pastry, sift the flours and salt into a large mixing bowl, making a well in the middle. Cut the butter (or lard) into pieces into a saucepan and add 180ml water (or 200ml if using lard). Place over a medium heat and as soon as it is bubbling fast, pour the fat / water mix into the flour bowl. Stir together using a wooden spoon to form a dough and then use your hands. It won’t need much kneading.

Separate off two-thirds of the dough. Roll it out on a lightly-floured worktop to a thickness of about 4mm and cut out a circle that covers the base of the tin. Lift the dough over and into the base. If it can go a little way up the sides of the tin then all to the good. Use more dough to roll pieces for the sides of the pie. This pastry is incredibly amenable to patching up and pressing pieces together. When you have the base and sides done, spoon in about a third of the filling mix, then scatter over half the grated gruyère. Repeat with another third of filling, the rest of the cheese, and finally the last of the celeriac/potato mix.

Take most of the remaining pastry and roll out to form a lid. Lift it onto the pie and bring the side pastry up and over the edges and press together, so you are building your pie to sit inside and below the top of the tin. Crimp as prettily as you can or want to.

The last of the pastry can be used to make decorations. I like to make stars or leaves and cut them out with biscuit cutters before pressing them on top.

Push the handle of a wooden spoon through the centre of the pie’s lid to make a steam hole. Beat the egg with a little water and brush over the pastry. Then put your beautiful pie into the oven, sitting it on the hot baking tray. Bake for 45 minutes, then lift the pie out and gently release and remove the springform ring. Return the pie to the oven for 15–20 minutes so that the pastry sides can brown a little too. It is ready when the pastry is beautifully golden on top.

Let the pie sit out of the oven for 5–10 minutes before slicing. It is a pie best eaten while still warm. Some sort of greens alongside are a very good idea.

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