Mary Berry’s Fish Pie with Rosti Topping Recipe

This comforting fish pie pairs a creamy, gently mustardy seafood filling with a crisp, golden rosti topping that stays beautifully crunchy at the edges. The flavour is classic and cosy, with flakes of tender fish in a silky sauce and a potato top that feels a little special without being fussy. It’s a straightforward, family-friendly bake that suits confident beginners and seasoned home cooks alike. Total time is around 1 hour 10 minutes, including baking.

Ingredients

For the fish filling

• 500g mixed fish (skinless cod, salmon, smoked haddock), cut into large chunks
• 150g cooked peeled prawns (optional)
• 1 bay leaf
• 300ml whole milk
• 1 small onion, finely chopped
• 1 small leek, trimmed and thinly sliced
• 100g frozen peas
• 2 tbsp chopped fresh parsley or dill

For the creamy sauce

• 40g unsalted butter
• 40g plain flour
• 250ml fish poaching milk (from above)
• 100ml double cream
• 1 tbsp Dijon mustard
• 1 tsp lemon zest
• 1 tbsp lemon juice
• Salt and freshly ground black pepper, to taste

For the rosti topping

• 900g floury potatoes (Maris Piper or King Edward), peeled
• 40g unsalted butter, melted
• 2 tbsp olive oil
• 1 tsp fine salt
• 1/2 tsp black pepper

Optional finish

• 2 tbsp grated mature cheddar
• Extra chopped herbs, to serve

How to Make Fish Pie with Rosti Topping

• Prepare the oven: Preheat the oven to 200°C or 180°C fan. Place a shelf in the middle of the oven so the pie cooks evenly and the topping colours nicely.
• Poach the fish: Pour the milk into a wide saucepan and add the bay leaf. Bring to a gentle simmer, add the fish pieces, and poach for 4–6 minutes until the fish is only just starting to flake. Lift the fish out with a slotted spoon and set aside. Measure out 250ml of the poaching milk for the sauce.
• Cook the onion and leek: Melt the butter in a saucepan over medium-low heat. Add the onion and leek and cook for 8–10 minutes until soft and sweet, without browning.
• Make the white sauce: Stir the flour into the buttery veg and cook for 1 minute. Gradually whisk in the reserved poaching milk until smooth, then simmer for 2–3 minutes until thickened. Stir in the cream, Dijon mustard, lemon zest, and lemon juice. Season to taste.
• Mix the filling: Gently fold the fish into the sauce, trying not to break it up too much. Stir in the peas and chopped herbs. Add the prawns (if using) right at the end so they stay juicy.
• Assemble the pie: Spoon the fish filling into a lightly buttered 2 litre baking dish and level the top. If you like, leave a little texture rather than smoothing it perfectly flat.
• Prepare the rosti topping: Coarsely grate the potatoes. Tip them into a clean tea towel and squeeze firmly over the sink until they’re very dry. Put the potato into a bowl and toss with melted butter, olive oil, salt, and pepper.
• Top and bake: Scatter the rosti mixture over the filling in an even layer, keeping it a little loose so heat can circulate. Sprinkle with cheddar if using. Bake for 35–40 minutes until bubbling at the edges and deeply golden on top.
• Cool briefly before serving: Rest the pie for 10 minutes. This gives the sauce time to settle so it serves neatly and stays creamy rather than runny.

Tips

Why is my rosti topping soft instead of crisp?

It almost always comes down to moisture. Squeeze the grated potato very dry in a tea towel, then toss with both butter and oil so it browns properly. Also make sure the topping is scattered, not pressed down firmly.

How do I stop the fish from overcooking?

Poach it gently and briefly, just until it starts to turn opaque at the edges. It finishes cooking in the oven, and that’s what keeps the flakes tender instead of dry.

What if my sauce turns lumpy?

Whisk in the warm poaching milk gradually and keep the heat moderate. If you do get a few lumps, whisk vigorously off the heat for a moment. In a pinch, pass the sauce through a sieve before adding the fish.

How can I add more flavour without making it too salty?

Smoked haddock adds plenty of savoury depth, so go easy on salt until the end. Lemon zest, Dijon mustard, and fresh herbs lift the whole pie without needing extra seasoning.

Serving Suggestions

• Steamed green beans or tenderstem broccoli
• Buttered peas or minted mushy peas
• A crisp side salad with a lemony dressing
• Roasted carrots or honey-glazed parsnips

Storage

Room temperature

Let the pie cool for no more than 2 hours, then refrigerate. Fish and dairy-based sauces should not be left out for longer.

Refrigerator

Cover the dish well and refrigerate for up to 2 days. Reheat in the oven at 180°C (160°C fan) for 20–30 minutes until piping hot throughout. If the top is browning too quickly, cover loosely with foil.

Freezing

Freeze in an airtight, freezer-safe dish for up to 2 months. Thaw overnight in the fridge before reheating. For the crispest rosti, reheat in the oven rather than the microwave.

Nutrition

• Calories: 520 kcal
• Carbohydrates: 42g
• Protein: 33g
• Fat: 25g
• Saturated Fat: 12g
• Sodium: 680mg

Nutrition values are estimates and will vary depending on the fish mix, brands, and exact portions used.

FAQs

Mary Berry’s Fish Pie with Rosti Topping Recipe

Recipe by Milli RoseCourse: Main CourseCuisine: BritishDifficulty: Medium

Servings

6

servings

Prep time

30

minutes

Cooking time

40

minutes

Total time

70

minutes

Calories

520

kcal

1

hour 

10

minutes

Creamy British fish pie packed with tender fish in a rich white sauce, topped with crisp, golden rosti potatoes. A hearty, make-ahead friendly family dinner.

Ingredients

• For the fish filling

• 500g mixed fish (skinless cod, salmon, smoked haddock), cut into large chunks

• 150g cooked peeled prawns (optional)

• 1 bay leaf

• 300ml whole milk

• 1 small onion, finely chopped

• 1 small leek, trimmed and thinly sliced

• 100g frozen peas

• 2 tbsp chopped fresh parsley or dill

• For the sauce

• 40g unsalted butter

• 40g plain flour

• 250ml fish poaching milk (from above)

• 100ml double cream

• 1 tbsp Dijon mustard

• 1 tsp lemon zest + 1 tbsp lemon juice

• Salt and freshly ground black pepper, to taste

• For the rosti topping

• 900g floury potatoes (Maris Piper or King Edward), peeled

• 40g unsalted butter, melted

• 2 tbsp olive oil

• 1 tsp fine salt

• 1/2 tsp black pepper

• To finish (optional)

• 2 tbsp grated mature cheddar

• Extra chopped herbs, to serve

Directions

• Preheat the oven to 200°C (180°C fan). Lightly butter a 2 litre baking dish.
• Gently poach the fish with the bay leaf in the milk for 4–6 minutes until just starting to flake. Lift fish out with a slotted spoon and reserve 250ml of the poaching milk.
• Soften the onion and leek in the butter for 8–10 minutes until tender but not coloured.
• Stir in the flour and cook for 1 minute. Gradually whisk in the reserved poaching milk, then simmer until thickened. Stir in cream, mustard, lemon zest and juice, and season.
• Fold in the fish, peas, herbs, and prawns (if using). Spoon into the baking dish.
• Coarsely grate the potatoes. Squeeze very dry in a clean tea towel, then toss with melted butter, olive oil, salt and pepper.
• Scatter the rosti topping evenly over the fish filling. Do not pack it down too firmly. Sprinkle with cheddar if using.
• Bake for 35–40 minutes until bubbling at the edges and the rosti is crisp and deep golden. If needed, finish under the grill for 2–3 minutes to colour.
• Rest for 10 minutes before serving so the filling settles and slices neatly.

Notes

• Squeezing the grated potato dry is the key to a crisp rosti topping.
• Keep the fish slightly undercooked when poaching; it will finish cooking in the oven.
• For a smokier flavour, use a little more smoked haddock and reduce added salt.
• Assemble up to 24 hours ahead and bake when needed.