Sift the flour into a large bowl and add the salt, sugar, and diced butter.

Rub the butter in flour with your fingertips until the mixture is like fine breadcrumbs.

Add the water gradually just enough to make a firm dough.

Knead the dough briefly on a floured surface and turn it into a ball.

Wrap in a cling film and rest in the fridge for at least 1 hour before rolling it out.

Soak dried porcini in 250ml boiling water for 15 minutes.

Spoon out the porcini mushrooms, roughly chop and keep the liquid for cooking the pie filling. Set them aside until needed.

Melt the butter in a large pan or wok on medium heat and then add the leeks.

Sauté the leeks for a few minutes, until slightly softened.

Turn the heat up and then add the mushrooms to the pan, sauté until softened and released their juices.

Add the carrots along with the garlic and cook for a few minutes, until the liquid from the mushrooms has evaporated.

Sprinkle on the flour and then add the porcini mushrooms. Cook for a minute, stirring continuously.

Pour in the milk and the soaking liquid from the mushrooms stirring all the time to avoid lumps, and continue to cook for a few minutes, until bubbling and the sauce has thickened.

Add the thyme, salt, freshly ground black pepper, and chili flakes (if using) to finish the filling off.

Transfer the filling to a 25 cm (10") diameter pie dish and let it cool down to room temperature before assembling your pie.

When the filling is cooled down to room temperature, take the pastry out of the fridge and leave it at room temperature for 10 minutes before rolling it out.

Preheat your oven to 180° C - 350° F (fan oven).

On a lightly floured surface, roll out the pastry slightly larger than the pie dish.

Cover the top of the pie dish with the pastry and trim off any excess with a knife.

Crimp the edge of the pastry along the rim of the dish using your thumb to seal the mixture. Brush the pastry with egg wash.

Make some decorations from the leftover pastry using a small knife or small cookie cutters if you want a fancy-looking pie.

Make a hole in the middle to let the steam out while cooking.

Cook your pie in the oven for about 25 minutes or until the pastry is golden brown.

Allow the pie to cool slightly before serving.