Bring a saucepan of water to the boil and carefully add two of the eggs. Boil for 9 mins, then drain and run under cold water. Once cooled, shell and roughly chop. Meanwhile, put the saffron in a cup, pour in the milk and set aside.

Melt the butter in a pan over a low heat, then add the leek, bacon and potatoes, and cook gently for 10 mins. Stir in the flour and cook for 2 mins. Add the saffron milk a little at a time, stirring well, then bring to a simmer and cook for 5 mins until the sauce has thickened. Pour in the cream, then stir in the chopped eggs and chives, and some seasoning.

Heat the oven to 200C/180C fan/gas 6. Pour the cream sauce into a rectangular ovenproof dish and arrange the fish with the heads pointing up. Unroll the pastry, making slits for the fish heads to poke through, then lay over the dish and guide the heads through the slits. Lightly beat the remaining egg, then brush the rim of the pie dish with some of it and press the pastry edges down firmly. Brush the top of the pie with the remaining egg, then put on a baking sheet and bake for 40-45 mins until puffed and dark golden.