Mary Berry Fish Pie With Crushed Potatoes​

The first time I tried making this version of fish pie, I was sceptical. No mash? Just crushed potatoes on top? Honestly, I thought it sounded a bit lazy. But I was short on time (and short on butter), so I gave it a go.

And thank goodness I did. Not only did it save me from boiling and mashing a mountain of spuds, but that golden, craggy potato top turned out to be the best part. It crisps up beautifully with just a drizzle of olive oil, and the soft chunks underneath soak up the lemony, creamy fish filling like a dream.

That said, my first go was a bit watery. I didn’t drain the spinach properly, and my sauce was more like soup. Let me show you how to avoid that—and why I now prefer this to the traditional kind.

Why This One Works So Well

Most fish pies can feel a bit heavy with all the mash and cream, but this one gets the balance just right:

• Crushed new potatoes instead of mash—faster, crispier, and less stodgy
• A light dill and lemon cream sauce that lifts the richness of the fish
• Wilted spinach for freshness and colour (but only if you drain it properly—trust me)
• Two types of fish for texture: flaky salmon and tender hake

Plus, because there’s no fiddly piping or mash spreading, it’s much quicker to pull together on a weeknight.

Ingredients + Why They Matter

• Butter (75g total) – For richness and softening the leeks. Don’t be tempted to swap for oil in the sauce—it won’t coat the fish the same way.
• Leek (1 large) – Softer and sweeter than onion, it melts right into the sauce.
• Plain flour (50g) – Thickens the base so the fish sits in a proper pie filling, not soup.
• Hot full-fat milk (600ml) – Helps keep the sauce silky. I once used cold milk and ended up with lumps.
• Fresh dill (1½ tbsp) – Bright, herby lift. Dried just doesn’t cut it.
• Lemon zest (½ lemon) – Adds zing and cuts through the creaminess.
• Salmon + hake (400g each) – They cook at the same rate and give contrast—oily and meaty vs light and delicate.
• Fresh spinach (200g) – Adds depth and a pop of green, but must be drained or it’ll water down the filling.
• New potatoes (800g) – Charlotte or any waxy variety works. Holds shape when crushed.
• Olive oil (2 tbsp + 2 tsp) – For mixing into the potatoes and crisping the top.

Making It Yours (Without Ruining It)

• No hake? I’ve swapped it for cod with no issues. Just cube it the same size as the salmon.
• Dairy-free? I tested this with oat milk and plant-based butter—it worked, but the sauce was thinner. Add a spoon of dairy-free cream to thicken.
• No dill? Fresh parsley gives a different but still lovely flavour.
• Want more veg? I’ve stirred in some cooked peas or sweetcorn before—both were great. Just keep the ratio of sauce to solids balanced.

Mistakes I’ve Made (And How to Avoid Them)

What Went Wrong	Why It Happens	How to Fix It
Watery filling	Didn’t drain spinach properly	Squeeze out every bit of moisture after wilting
Mushy fish	Over-stirred it in the sauce	Gently fold it in and don’t keep it on heat too long
Soggy topping	Added potatoes while filling was hot	Let filling cool before adding potatoes

How to Make Mary Berry’s Fish Pie with Crushed Potatoes

1. Start with the sauce
   Butter a large baking dish. In a large pan, melt 50g of the butter. Add sliced leek and cook 3 minutes until soft. Stir in flour, cook 1–2 minutes.
2. Make it creamy
   Gradually add the hot milk, whisking constantly. Let it simmer until thickened, then stir in dill, lemon zest, salt, and pepper.
3. Add the fish
   Gently fold in the cubed hake and salmon. Cook on low for 2 minutes—just enough to coat it in sauce. Pour into the baking dish and let it cool slightly.
4. Cook the spinach
   Melt the remaining butter in a frying pan. Add spinach and stir for about 2 minutes until wilted. Drain thoroughly, pressing with a spoon. Roughly chop and set aside.
5. Prepare the potatoes
   Boil new potatoes in salted water until just tender (about 15 minutes). Drain and lightly crush with a fork in the pan. Stir in 2 tablespoons of olive oil, salt, and pepper.
6. Assemble
   Spread spinach over the cooled fish mixture. Pile the crushed potatoes on top—don’t pack them down. Drizzle with remaining olive oil.
7. Bake
   Bake at 200°C (fan 180°C) / 400°F / Gas 6 for 30 to 40 minutes until the top is crisp and golden and the edges are bubbling.

Tips From My Kitchen

• I always let the fish mixture cool slightly before adding the potatoes—prevents sinking and keeps the texture right.
• I use a fork, not a masher, to crush the potatoes. You want rough chunks, not puree.
• Don’t skip the drizzle of olive oil before baking—it makes the top properly golden.
• I often make the filling in advance and refrigerate it until I’m ready to top and bake.

Storage + Serving

• In the fridge: Keeps well for 2 days. Reheat in the oven at 180°C (fan 160°C) / 350°F until piping hot.
• In the freezer: Freeze in portions for up to 3 months. Defrost in the fridge overnight and reheat thoroughly.
• To serve: Perfect with steamed greens or a lemony salad on the side.

FREQUENTLY ASKED QUESTIONS

Q: Can I make this ahead of time?
Yes. Assemble the full dish up to the point of baking, cover, and refrigerate. Bake just before serving.

Q: Can I use frozen fish?
Yes, but defrost it completely and pat dry before adding. Otherwise, you’ll get too much liquid in the sauce.

Q: Why crushed potatoes instead of mash?
They’re faster, crispier, and lighter. Plus, you don’t need milk or butter in the mash—just olive oil and seasoning.

Q: Can I add prawns?
I’ve tried it with a handful of raw king prawns—tossed in at the same time as the fish. Delicious.

Q: Is this suitable for kids?
Absolutely. The sauce is mild and creamy, and the lemon zest isn’t overpowering. I just skip the dill if I’m cooking for picky eaters.

Try More Recipes:

• Mary Berry Potato Rösti With Onion
• Mary Berry​ Roast New Potatoes With Garlic And Rosemary
• Mary Berry Parmentier Potatoes
• Mary Berry Roasted Sausage and Potato Supper