Ingredients

Step by step

1. Butter a 22cm springform cake tin (about 6.5cm deep). For the pastry, put the flour, a pinch of salt and the diced butter in a food processor (or rub it in by hand). Whiz until it forms fine crumbs then tip into a mixing bowl and, using a fork, mix in 2-4 tablespoons cold water, until it starts to clump together. Lightly knead and turn out onto a floured work surface.
2. Cut a third of the pastry off and set aside. Roll out the larger piece between 2 large pieces of baking paper to form a 34-36cm diameter circle. Remove the top piece of paper and flip the pastry over to line the tin, remove the paper and mould the pastry into the tin.
3. Reusing the baking paper, roll the remaining third of pastry into a disc, about 22cm diameter, large enough to cover the top of the pie. Leave between the paper and place on a plate in the fridge along with the lined cake tin. Chill for 30 minutes.
4. Preheat the oven to 200°C, fan 180°C, gas 6. Put a baking tray in the oven to preheat at the same time. For the filling, heat 2 tablespoons olive oil in a deep nonstick frying pan over a moderate heat. Once hot, add the sliced leeks and fry for 10 minutes, stirring occasionally, or until softened. Tip into a bowl; cool for 10 minutes.
5. Meanwhile, put the eggs, egg yolks and mustard in jug. Beat together with a fork and then mix in the cream and season well with salt and pepper. Mix a quarter of this mustard cream into the leek mixture.
6. Drop the spinach into a large pan of boiling water. As soon as it returns to the boil, drain in a colander and cool under cold running water. Squeeze dry and roughly chop. Place in a bowl, mix in a quarter of the mustard cream.
7. Cut the chicken breasts into 2cm pieces. Put the chicken, bacon and lemon zest in a bowl with another quarter of the mustard cream and lightly season. Spoon the leek mixture into the bottom of the pie. Cover with the chicken, before covering with the spinach mixture. Pour most of the remaining mustard cream over the top, reserving 1 tablespoon to glaze the pastry.
8. Brush the pastry rim with a little of the mustard cream and gently lay the pastry lid on top. Seal the pie by pinching the pastry together with a fork. Trim the excess pastry from the rim and brush the lid with the rest of the mustard cream. Make an air hole in the centre of the lid and bake in the centre of the oven for 1 hour 15 minutes until golden. Cover with foil halfway through if it starts to darken.
9. Place the pie on wire rack and leave to cool in the tin for 2 hours before gently unclipping and releasing the pie – but leave it on the tin base. Once cool, place in the fridge overnight to firm up. To serve, remove the tin base and transfer the pie to a serving plate and cut into wedges.