Mary Berry Fish Pie with Leeks Recipe

This Mary Berry-inspired fish pie with leeks is the kind of cosy, dependable supper that never lets you down. You get tender flakes of fish and sweet, silky leeks in a creamy mustard sauce, all tucked under a fluffy, buttery mash topping that goes golden in the oven. It’s straightforward enough for a confident weeknight cook, but special enough for Sunday lunch. Total time is about 1 hour 10 minutes from start to serving.

Ingredients

For the Fish and Leek Filling

450g mixed fish fillets (skinless, boneless white fish and/or smoked haddock), cut into large chunks
300ml whole milk
1 bay leaf
2 leeks, trimmed and thinly sliced (about 250g prepared)
30g unsalted butter
2 tbsp plain flour
1 tbsp Dijon mustard
1 tbsp lemon juice
2 tbsp chopped fresh parsley
100g frozen peas
Salt and freshly ground black pepper, to taste

For the Mash Topping

900g floury potatoes (Maris Piper or King Edward), peeled and cut into chunks
50g unsalted butter
80ml warm milk (plus a little extra if needed)
60g mature cheddar, grated (optional)
A pinch of nutmeg (optional)
Salt and freshly ground black pepper, to taste

To Assemble

Butter, for greasing the dish

How to Make Mary Berry Fish Pie with Leeks

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.
Boil the potatoes: Put the potatoes into a large pan of salted water. Bring to a boil and cook for 15–18 minutes, until a knife slips in easily. Drain well and leave to steam-dry for 2 minutes.
Poach the fish: Add the fish to a wide pan with the milk and bay leaf. Bring to a gentle simmer, then cook for 3–4 minutes until the fish is only just starting to flake. Lift the fish out with a slotted spoon and set aside. Reserve the milk and discard the bay leaf.
Soften the leeks: Melt 30g butter in a pan over medium-low heat. Add the sliced leeks and cook for 8–10 minutes, stirring often, until soft, sweet, and silky. Try not to let them brown.
Make the creamy sauce: Stir the flour into the leeks and cook for 1 minute. Gradually whisk in the reserved milk a little at a time, then simmer for 2–3 minutes until thickened and smooth.
Finish the filling: Stir in the Dijon mustard, lemon juice, and parsley. Season with salt and pepper, then add the peas. Fold the fish through gently so it stays in nice chunks.
Mash the topping: Mash the potatoes with 50g butter and warm milk until fluffy. Season well, then stir in the grated cheddar and nutmeg if using.
Assemble the pie: Butter a 2-litre baking dish. Spoon in the fish and leek filling, then spread the mash on top, pushing it right to the edges. Rough up the surface with a fork for crispier ridges.
Bake: Bake for 20–25 minutes until bubbling at the edges and golden on top. For extra colour, pop it under the grill for 1–2 minutes at the end, keeping a close eye on it.
Cool briefly and serve: Let the fish pie stand for 10 minutes before serving. This gives the sauce a chance to settle so it plates up neatly.

Tips

Why is my fish pie watery?

This is usually down to not thickening the sauce enough or adding fish that releases lots of liquid. Simmer the sauce until it coats the back of a spoon, and steam-dry the potatoes properly so the topping does not weep moisture into the filling.

How do I stop the mash from sinking into the filling?

Make sure your filling is thick and not boiling hot when you top it. If it’s very loose, simmer it for another minute or two. Spreading the mash gently from the edges inward also helps it sit on top.

Can I make this fish pie ahead of time?

Yes. Assemble the pie, cool completely, cover, and refrigerate for up to 24 hours. Bake until piping hot all the way through; you may need an extra 10–15 minutes if it goes in cold.

What fish works best for a Mary Berry-style fish pie?

A mix gives the nicest flavour and texture. Try cod or haddock for chunky flakes, plus a little smoked haddock for depth. If your mix is very smoky, keep the mustard and seasoning a touch lighter until you taste.

Serving Suggestions

Buttered peas or green beans
Steamed broccoli or tenderstem
A crisp green salad with a lemony dressing
Pickled onions or gherkins on the side for contrast

Storage

Room Temperature

Let the pie cool for no more than 1–2 hours before refrigerating. Because it contains fish and dairy, it should not be left out longer than that.

Refrigerator

Store covered in the fridge for up to 2 days. Reheat in a 180°C fan oven until piping hot throughout. If you reheat in the microwave, finish in the oven if you want the mash to stay crisp.

Freezing

Freeze the baked (or unbaked) pie well wrapped for up to 2 months. Thaw overnight in the fridge, then bake until the centre is steaming hot. If baking from frozen, cover with foil and bake longer, removing the foil for the final 15 minutes to brown the top.

Nutrition

Calories: 520 kcal
Carbohydrates: 45 g
Protein: 33 g
Fat: 24 g
Saturated Fat: 12 g
Sodium: 780 mg

Nutrition values are estimates and will vary depending on the fish and brands used.

FAQs

Can I use frozen fish for fish pie?

Yes. Thaw it fully in the fridge first, then pat dry with kitchen paper before poaching or adding to the sauce. Excess water from frozen fish can thin the sauce, so make sure your sauce is nicely thick before assembling.

Do I have to poach the fish in milk first?

Poaching gives a gentle, tender texture and the reserved milk makes the sauce taste richer. If you’re short on time, you can cook the sauce separately and add raw fish chunks, but you’ll need to bake a little longer to ensure the fish is cooked through.

What can I use instead of leeks?

Finely sliced onions work well, or a mix of onions and fennel for a softer, sweeter flavour. Cook them gently until very soft before making the sauce so they don’t stay crunchy.

How do I know the fish pie is hot enough to serve?

Look for bubbling around the edges and a golden top. The centre should be piping hot; if you have a thermometer, aim for at least 75°C in the middle. Resting for 10 minutes helps the filling settle without cooling it too much.