For the poached chicken, place all the ingredients in a large saucepan over high heat and bring to the boil. Reduce heat to medium and simmer for 25-30 minutes or until chicken is cooked. Remove from the heat and place chicken in a bowl and tear into chunks. Strain stock and reserve, discarding the solids.

Heat a large, deep heavy-based non- stick frypan over high heat. Add oil and butter with the pancetta, leek, garlic and herbs. Cook, stirring frequently, for 6-8 minutes until leek has softened and pancetta starts to brown. Add the mushrooms and cook for a further 5-6 minutes until the mushrooms have softened. Add Pernod, scraping the bottom of the pan with a spoon and reduce until evaporated.

Scatter over flour and cook, stirring continuously, for 1-2 minutes until flour is toasted. Stir in reserved stock, cream and parmesan, and bring to the boil. Simmer for 8-10 minutes until very thick. Stir in chicken, season to taste and remove from the heat. Refrigerate until cooled completely.

Transfer cooled mixture to a round 2.25L-capacity pie or ovenproof dish. Top with pastry and press to seal, trimming edges to fit if needed. Pierce a hole in the centre of the pastry to release steam while cooking. Brush pastry with egg wash, scatter over freshly ground black pepper and sea salt. Bake for 45 minutes or until the pastry is golden. Serve immediately.