Preheat the oven to 180C/350F/gas 4.
Grease the pie dish with butter.
Place the butter in the saucepan and heat until melted and starting to foam. Add the the onion and bacon and cook until the onion is translucent and the bacon starts to brown.
Add the flour and stir in well, then slowly add the cider and fish stock, stirring well to prevent lumps forming. Bring to the boil, reduce the heat and simmer for 10 minutes.
Add the cream and simmer vigorously until thickened and reduced by half.
Remove from the heat, add the parsley and chopped egg and season with salt and pepper. Leave to cool.
Cut the fillets of fish in half and lay them in the pie dish and season. Pour the sauce over the fish.
To make the pastry sift the flour and salt into the large mixing bowl.
Add the butter and stir in loosely, making sure all the butter chunks are coated in flour.
Add the water and stir in until you have a wet, lumpy dough.
Cover with clingfilm and place in the fridge for 30 minutes.
Place the dough on a floured work surface and shape into a rectangular block.
Roll the dough to a rectangle three times longer than it is short, keeping the edges straight and even. The rolled-out pastry should have a marbled effect from the lumps of butter.
Fold the top third down to the centre, then the bottom third up and over that.
Give it a quarter turn and roll out again to the original sized rectangle.
Repeat the folding, turning and rolling out 3 more times or until the marbling effect has disappeared. Fold once more and place in the fridge for 30 minutes.
Remove from the fridge, place the chilled dough onto the floured work surface and roll out to a thickness of about 3mm in a shape that will cover the pie dish with at least a 1cm overhang.
Brush the rim of the pie dish with beaten egg and place the pastry over it.
Press down the edge of the pastry onto the rim and then crimp and trim it.
Make 6 small slits in the pastry and push the reserved fish heads through them so they appear to be ‘looking upwards to the stars’. Make sure the fish ‘skeletons’ are still attached to the heads, so they are supported beneath the pie crust and don’t sink into the pie as it cooks.
Brush the top of the pie with the beaten egg and place in the oven and bake for 40-45 minutes until the pastry is golden and risen.
Remove from the oven and serve immediately.
