Fish Pie
Flaked salmon, cod, and king prawns in a creamy cheese sauce, topped with buttery mashed potato and baked until golden — a British comfort food classic.
- 1 kg (2 1/2 lb) floury potatoes, such as Maris Piper, peeled and chopped into large chunks
- 1 1/2 tablespoons butter
- 3 tablespoons double cream (heavy cream)
- Large pinch salt and pepper
- 600ml (2 1/2 cups) full-fat milk
- 2 boneless salmon fillets (approx. 250g/8.8oz altogether)
- 1-2 boneless cod or haddock fillet (approx. 250g/8.8oz altogether)
- 15 king prawns/shrimp, cooked or raw and de-veined (approx. 170g/6oz raw weight)
- 2 tablespoons plain (all-purpose) flour
- 1 1/2 tablespoons butter
- 150g (1 1/2 packed cups) grated mature cheddar cheese
- Pinch black pepper
- 1 tablespoon chopped chives, for serving
- Peas, for serving
- Sweetcorn, for serving
- Preheat the oven to 400°F (200°C fan).
- Place the potatoes in a pan and cover with cold water. Bring to the boil, then simmer for 15 minutes, until tender.
- Drain the potatoes and mash with a potato masher or ricer. Stir in half of the first batch of butter, the cream, and a pinch of salt and pepper. Set the mash aside.
- Place the milk in a large saucepan with the salmon fillets and the cod or haddock. Bring to the boil and simmer for 2 to 3 minutes — if using raw prawns, add them in for the last minute of cooking. By this point the fish should be cooked through and starting to flake apart easily.
- Place the flaked fish and prawns (adding cold, already-cooked prawns now if you used those) into a large baking dish, removing and discarding the skin if the fish wasn't already skinless.
- Pour the cooking liquid into a jug and set it aside — you'll need it for the sauce.
- Melt the remaining butter in the same milk pan, then stir in the flour. Cook over medium heat, mixing with a wooden spoon, for about a minute to cook out the raw flour taste.
- Slowly whisk in the reserved milk with a balloon whisk, working gently rather than whisking hard, which would make the sauce frothy instead of smooth. The sauce will begin to thicken after a few minutes of gentle heat and stirring.
- Turn off the heat and stir through half of the cheese and a pinch of black pepper until melted and smooth.
- Pour the sauce evenly over the fish and prawn mixture in the baking dish.
- Spoon the mashed potato over the top, then use a fork to spread it out and create a lined, textured pattern — this extra surface area helps the topping crisp up nicely in the oven.
- Sprinkle the remaining cheese over the mashed potato and bake for 15 to 20 minutes, until the cheese is melted and golden brown.
- Top with the chopped chives and serve hot alongside peas and sweetcorn.
Chef's Note: Poaching the fish directly in the milk that later becomes the sauce is the real trick behind this pie's flavor — that milk picks up all the delicate fish flavor as it simmers, so nothing goes to waste and the sauce tastes far more of the sea than a plain white sauce would. Whisking gently rather than vigorously when adding the milk back to the roux matters too; a hard whisk introduces air and leaves you with a frothy, less silky sauce.
Forking lines into the mashed potato topping before baking isn't just decorative — it genuinely increases the surface area that can crisp and brown, giving you more of that golden, slightly craggy texture on top. This pie also freezes well: assemble it completely but stop before baking, then freeze, defrost fully in the fridge overnight, and bake straight from there until golden and bubbling.
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