Fish Pie – The Secret to Perfectly Fluffy & Golden Mash Topping

Discover the secret technique for achieving an incredibly fluffy, golden potato topping for your fish pie. We’ll show you how to make a rich, flavourful béchamel sauce loaded with cod, haddock, salmon, and prawns, and topped with buttery, egg-enriched mash that crisps beautifully in the oven. This comforting fish pie recipe is perfect every time!

Ingredients

For the Fish Filling
• Cod Fillet: 300 g, boneless, skinless, cut into chunks
• Haddock Fillet: 200 g, boneless, skinless, cut into chunks
• Salmon Fillet: 200 g, boneless, skinless, cut into chunks (optional)
• Smoked Haddock: 150 g, boneless, skinless, cut into chunks
• Prawns: 150 g, raw, peeled and deveined (optional)

For the No-Water Mashed Potato Topping
• Floury Potatoes (e.g. Maris Piper or King Edward): 1 kg, peeled and chopped
• Unsalted Butter: 100 g
• Egg Yolks: 2
• Salt: to taste

For the Cheddar Cheese Sauce
• Unsalted Butter: 40 g
• Leek: 1 medium (approx. 200 g), finely sliced
• Plain Flour: 40 g
• Whole Milk: 600 ml
• Salt: ½ tsp (adjust to taste)
• White Pepper: ½ tsp
• Dijon Mustard: 1 tsp (optional)
• Ground Nutmeg: ¼ tsp (optional, especially if using cream)
• Mature Cheddar Cheese: 100 g, grated

Method
1. To make the mash, place the peeled and chopped potatoes into a cold, heavy-based pan along with the butter. Cover and cook over low heat for 45–60 minutes, stirring occasionally to prevent sticking. The potatoes will gently steam in their own moisture. Once fully softened, mash them thoroughly with a fork or masher until smooth. Let the mash cool to around 60°C, then mix in the egg yolks until fully incorporated. Season with salt to taste and set aside.

2. If time allows, coat the cod, haddock, and salmon (if using) with potato starch and let sit for a few minutes. Rinse under cold water until it runs clear, then pat dry. This step helps remove surface proteins and impurities, improving flavour and texture—particularly helpful for supermarket fish. Do not treat the smoked haddock or prawns this way.

3. To make the cheese sauce, melt the butter in a saucepan over medium-low heat and add the sliced leeks. Sweat gently for 5–7 minutes without colour until soft. Stir in the flour and cook for 1–2 minutes to form a roux. Gradually whisk in the cold milk a little at a time to prevent lumps. Simmer for about 5 minutes until thickened, then season with salt, white pepper, Dijon mustard, and nutmeg. Remove from the heat and let the sauce cool below 70°C before stirring in the grated cheddar. Stir until smooth. If you prefer a silky texture, you may strain the sauce at this stage.

4. Assemble the pie by evenly distributing the raw fish and prawns in a 1.6 L pie dish. Pour the cheese sauce over the fish, gently stirring to ensure even coating. Chill the dish in the fridge for about 30 minutes to allow the sauce to firm up slightly—this makes it easier to spread the mash over the top.

5. Preheat your oven to 200°C (fan 180°C). Spoon the cooled mashed potatoes over the fish filling and spread evenly. Use a fork to create texture on the surface, which will enhance browning. For an even more golden finish, brush the top lightly with melted butter. Bake for 25–30 minutes, or until the top is golden brown and the filling is bubbling around the edges.

Serving Suggestions
Serve hot with steamed greens such as peas, spinach, or cabbage. Buttered carrots or a light green salad also make excellent sides.

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