Fabulous Fish Pie

Method

Preheat the oven to 200°C/180°C fan/gas 6.

Put the potatoes in a large pan of salted boiling water, cover and simmer for 15–20 minutes or until tender.

Meanwhile, put the milk and bay leaf in a deep-sided frying pan, season and slowly bring to the boil over a medium heat. Add the fish fillets, then reduce the heat and gently poach for 4–6 minutes. Using a slotted spoon, lift the fish onto a plate to cool slightly. When cool enough to handle, check for any stray bones, keeping the fish in large chunks. Strain the milk into a jug.

Drain the cooked potatoes and allow to steam in the colander for a few minutes to dry out. Tip back into the pan and mash the potatoes well with a potato masher or pass through a ricer for super-smooth mash. Beat in the crème fraîche and half the butter and season with salt and white pepper.

Melt the remaining butter in a saucepan over a low-medium heat. Add the leeks and cook for 6–8 minutes until softened but not coloured. Increase the heat to medium, stir in the flour and cook, stirring, for 1–2 minutes. Gradually pour in the reserved milk, whisking constantly, then simmer over a low heat for 6–8 minutes, stirring occasionally until thickened. Stir in the mustard, lemon zest and a small squeeze of juice, and check for seasoning. Add the parsley, chives, prawns and peas.

Lightly grease a deep ovenproof pie dish or medium lasagne dish with butter. Add the fish then spoon over the sauce to cover. Let rest for a few minutes to allow a slight skin to form, then spoon or pipe over the potatoes to cover completely. Smooth with a spatula (unless piped) and scrape the surface with a fork to fluff the surface slightly. Scatter over the grated cheese (if using) and bake for 20–25 minutes or until heated through and the top is golden.

Serve garnished with some fresh parsley.