Cut the squash in half lengthwise, and discard the seeds, and transfer to a baking tray. Pop the garlic cloves inside the hole where the seeds were. Season with the salt and drizzle both squash halves with 2 tbsp of olive oil. Roast in the hot oven for about 50 minutes, until the flesh is soft and tender. Remove from the oven and allow to cool. Once cool, scoop the flesh from the skin and mash with 1 tbsp olive oil and the grated nutmeg. Taste and season then set aside to cool fully.

Remove the core from the cabbage and thinly slice. Pick the oregano leaves from the sprigs. Put the cabbage in a large saucepan with 100ml water. Add the oregano, star anise, bay, red wine vinegar, sugar, and salt and cover with a lid. Bring to a simmer, and cook gently for 40 minutes, stirring every 15 minutes so that it doesn’t catch. Taste and add more salt and pepper if you like. Remove from the heat and allow to cool.

Peel and finely chop the onion. Peel and crush the garlic. Pick the thyme leaves from the sprigs. Roughly chop the mushrooms and chestnuts. You can do this in a food processor, but be careful not to chop them too small. Wipe out the bowl of the food processor. Add the bread and pulse to breadcrumbs. Melt the butter in a frying pan over medium heat, then add the onion and cook for 5 minutes to soften. Stir through the garlic and thyme. Increase the heat to high then add the mushrooms and chestnuts. Cook for 7-10 minutes, constantly stirring, so that the mushrooms cook and the water from the mushrooms evaporates. Remove from the heat and stir through the breadcrumbs, porcini powder and a good pinch of salt and pepper. Remove from the heat and allow to cool.

Rip the cavolo nero leaves from stalk, and tear into even-sized pieces. Bring a pot of salted water to the boil. Using a steaming basket, place the cavolo inside the pot and steam until wilted, about 4 minutes. Remove from the heat and rinse under cold water to stop the cooking process.

Preheat the oven to 200*C fan setting. Before you begin to build, it is important that each vegetable layer is fully cooled. Roll one pastry block on a lightly floured surface into a 30cm round and transfer to a lined baking tray. Spread the butternut squash over the base, leaving a 2cm margin all the way around. Next, pile on the stuffing, followed by the cabbage and the cavolo nero. Roll out the other block of pastry to a 35cm diameter. Drape the lid on top of the pie filling. Using your fingers, seal it round the edges. In a small bowl, whisk together the milk and mustard and brush it all over the pastry. The mustard will let the pastry go a nice golden color. Chill in the fridge for at least 20 minutes or overnight. Bake in the hot oven for 30-35 minutes until the pastry is golden brown and crisp.