Fish Pie with Mashed Potato Topping
Why this recipe works
- Gentle poaching: Poaching the fish in milk keeps it tender and creates a flavourful base for the parsley sauce.
- Creamy, structured filling: A roux thickens the warm poaching milk into a smooth sauce that coats the fish without becoming watery.
- Balanced richness: Dijon mustard, lemon and a little nutmeg lift the dairy-rich sauce and keep the pie from feeling heavy.
Get the most out of this recipe
Timing notes
- Active prep is front-loaded: Most of the hands-on work is making the mash, poaching the fish and preparing the sauce; once assembled, the pie finishes in the oven.
- Let it settle before serving: A short rest after baking helps the creamy filling thicken slightly, making the pie easier to spoon from the dish.
- Serve hot: Fish pie is best served while the sauce is still loose and the potato topping is warm and lightly golden.
Texture tips
- Steam-dry the potatoes: Returning the drained potatoes to the hot pot briefly removes excess moisture, giving the mash a lighter texture.
- Rough up the topping: Forking the mash before baking creates ridges that brown more readily and give the top better texture.
- Keep the fish just cooked: Stop poaching when the fish is only just opaque; it will finish cooking as the pie bakes.
Ingredient notes
- Use a mix of fish: Smoked haddock adds savoury depth, while mild white fish keeps the filling balanced rather than overly smoky.
- Use lemon to lift the sauce: Lemon should brighten the creamy filling without overpowering the fish, so adjust it to taste.
- Keep the nutmeg subtle: Nutmeg works best as a background note in the white sauce, adding warmth without becoming dominant.
Make-ahead tips
- Assemble in advance: The pie can be assembled ahead, cooled, covered and refrigerated before baking until piping hot.
- Freezes well: Cool completely, wrap well and freeze; thaw overnight in the fridge before reheating.
- Reheat gently: Reheat in a 180°C (355°F) oven until piping hot all the way through.
Equipment you'll need
Ingredients
Instructions
- Heat the oven to 200°C (390°F). Peel the potatoes, cut into even chunks, and put into a large pot with cold water and 1 tsp of the fine sea salt.
- Bring the potatoes to the boil, then simmer for 15 to 20 minutes until very tender. Drain well in a colander and return to the hot pot for 1 minute to steam-dry.
- Add 50 g of the unsalted butter to the potatoes and mash until smooth. Pour in 100 ml of the whole milk and mash again until creamy; season with the remaining 1 tsp fine sea salt, then set aside.
- Meanwhile, pour 550 ml of the whole milk into a saucepan and add the bay leaves. Peel and halve the yellow onion and add it to the pan, then bring just to a gentle simmer over medium heat.
- Add the smoked haddock and white fish fillet to the hot milk and keep it at a bare simmer for 6 to 8 minutes, until the fish is just turning opaque and flakes at the edges. Lift the fish out to a plate and leave to cool slightly; discard the bay leaves and onion, and keep the milk.
- Melt the remaining 30 g unsalted butter in a saucepan over medium heat. Whisk in the plain flour and cook for 1 minute, then gradually whisk in the reserved warm milk until smooth.
- Simmer the sauce for 3 to 5 minutes, whisking often, until thick enough to coat the back of a spoon. Whisk in the Dijon mustard, ground nutmeg, and a squeeze of lemon juice.
- Roughly chop the fresh parsley and stir most of it into the sauce, reserving a little for the top. Flake the fish into large chunks, checking for any bones, then fold it gently into the sauce.
- Tip the fish and sauce into a baking dish and let it stand for 5 minutes so it settles slightly. Spoon the mash over the top and spread to the edges; rough it up with a fork and scatter over the reserved parsley.
- Bake for 25 to 30 minutes until bubbling at the edges and golden on top. Rest for 5 minutes before serving with extra lemon wedges for squeezing.
Recipe notes
Tips
- Keep the poaching milk warm when you make the sauce; it helps the roux thicken smoothly with fewer lumps.
- For the best texture, stop poaching the fish when it is only just opaque, as it will finish cooking in the oven.
- If serving vulnerable groups, make sure the pie is baked until piping hot all the way through.
Substitutions
- Replace Dijon mustard with whole-grain mustard for a milder heat and a coarser texture.
- Replace lemon with lime for a slightly sharper citrus finish.
Storage
- Refrigerate up to 2 days
- Cool completely, then cover and refrigerate for up to 2 days. Reheat in a 180°C (355°F) oven for 20 to 25 minutes until piping hot; if frozen, thaw overnight in the fridge before reheating.
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Recipe overview
- Servings: 4 servings
- Total time: 1h 25min (35min active)
- Difficulty: Medium
- Cuisine: British
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Allergens:
Fish Gluten Milk Wheat
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