1) Preheat the oven to 200C/400F/Gas 6. 2) Fry the shallots for a few minutes in the oil then add the fish stock and cream. 3) Bring to the boil and season then turn off. 4) Place the fish, mushrooms and chives in the dish, season with salt and pepper then pour the sauce over and fold in gently. 5) Roll out the pastry to twice the size of the ovenproof dish. 6) Sprinkle one half with the grated cheese. 7) Fold the pastry over sealing the cheese inside and roll very lightly to seal. 8) Top the pie with the pastry, trim off any excess and brush with the beaten egg. 9) Bake for 25-30 minutes until golden.