smoked fish pie

serves 10. hands-on time 35 min, simmering time 20 min, oven time 25-30 min

make ahead:
Assemble the pie to the end of step 5 up to 24 hours in advance. Keep covered in the fridge. Or wrap in a double layer of cling film and freeze for up to 3 months. Defrost fully before baking.

This makes a very large pie. You could make two pies using 2 x 1.5 litre dishes, then freeze one (see above).

for the filling
1 litre whole milk
100g unsalted butter
100g plain flour
3 tbsp spring onions, chopped
2 tbsp small capers, rinsed and drained
1 tbsp English mustard
5 tbsp chopped curly-leaf parsley
600g un-dyed smoked haddock, diced
150g smoked salmon, cut into strips
150g smoked mackerel, cut into bite-size pieces

for the mash
1.5kg floury potatoes, such as maris piper, cut into even chunks
100g unsalted butter
200ml whole milk
150g parmesan, grated

you'll also need...
2.5 litre ovenproof dish (see tip)

for the mash
Put the potatoes in a pan of salted water, bring to the boil, then reduce the heat and simmer for 20 minutes or until tender.

Drain the potatoes and let them sit in the colander for a few minutes, then return them to the pan. Mash until smooth, then beat in the butter and milk. Season and set aside.

Meanwhile, heat the oven to 180°C/160°C fan/gas 4. For the filling, pour the milk into a large saucepan and bring to a simmer. Melt the butter in another large saucepan, then add the flour and cook, stirring, for 1-2 minutes; don't let it brown. Gradually whisk in the hot milk, then bring to a simmer and cook over a low heat for 20 minutes, stirring occasionally.

Take the pan off the heat and stir the spring onions, capers, mustard and parsley into the sauce. Season with salt and pepper, then add the fish and stir gently to combine.

Tip the fish mixture into a large baking dish, then spoon or pipe the mashed potatoes on top. Scatter over the grated parmesan.

Put the dish on a baking sheet and bake for 25-30 minutes until piping hot and golden on top. Serve straightaway with a tomato and cucumber salad or buttered leeks tossed with a little mint.

PER SERVING 585kcals, 31.4g fat (17.4g saturated), 31.8g protein, 41.9g carbs (7.4g sugars), 1.9g salt, 3.9g fibre