This Easy Fish Pie with leeks and mashed potato has a lovely thick white sauce. A homemade fish pie is really something quite special. Less salty than many shop bought ones and lots more colour and flavour. I add lemon zest to the filling as it really brings out the flavour and lemon goes so well with fish. I've designed this recipe with no waste and packed it full of vegetables for a great one pot dish. For more easy one pot meals topped with mashed potato, you might also like my Simple Cottage Pie or Vegetarian version packed with pulses in a tomato sauce

Recipe Tips and Variations
- The beauty of a fish pie is that you can use any fish. I like a combination of white fish, smoked fish and prawns. You could substitute one of these for an oily fish such as salmon or trout. There is also nothing wrong with just using one type of fish if you prefer.
- Leave the skin on the fish whilst it is poached as it will hold the fish together. Once the fish is cooked, it is much easier to flake and leave the skin behind.
- There's no need to defrost the cooked prawns or peas before adding them to the fish pie mix. They will defrost and cook in the sauce.
- I use kale, leeks and peas in this recipe as they add a slight sweetness which I really like. You could also use cabbage, spinach, broccoli or sweetcorn. Adding the vegetables to the sauce makes this a great one pot dish.
- To make the white sauce, I use the milk that is used to poach the fish. This way you keep all the flavour and nothing is wasted.
- The best potatoes to use for mash are Desiree or Maris Piper potatoes in the UK and Russets or Yukon Gold in the US. These are higher starch potatoes and will give a light fluffy mash. Waxy potatoes are more difficult to mash and you can end up with a potato paste rather than fluffy mash. You could also try using sweet potatoes instead or half and half.
- To make sure your mash doesn't sink into the filling, let your cooked potatoes steam for a few minutes. This helps dry them out a little. Watery potatoes will weigh heavy and will seep into the filling. When adding the mashed potatoes, use a dessert or tablespoon and spoon it on one spoonful at a time. Start at the edges and work inwards towards the middle. Once you've covered the filling, you can go over the top with a fork to make a pattern or little grooves in the potato that will crisp up nicely in the oven.
FAQ's about Fish Pie
There is no need to serve extra vegetables on the side as it's all added in, making it a great one pot dish. If you like you could serve it with a simple green salad, just to add some colour to the plate or an extra portion of any green vegetable.
Yes fish pie can be reheated once. Cover the top with foil to prevent the top from browning any further. Reheat in the oven at 180C/350 F/gas mark 4 for about 40 minutes until piping hot. To check if it is piping hot in the middle, insert a fork, leave for a few seconds and then test on the back of your wrist to check if the fork is hot. It is best to defrost the pie first before reheating. If reheating from frozen, this will take around 1 ½ hours.
Yes fish pie can be frozen for around 3 months. After 3 months it will still be safe to eat, but the texture may change slightly. If you are planning on freezing the fish pie, it is best frozen once assembled but before being cooked in the oven. Let it cool then cover it and place in the freezer. If your fish pie has not already been cooked, leave it uncovered when reheating it so the top goes golden brown and crisp.
It will keep in the fridge for 2-3 days. You can also assemble it, keep it in the fridge and cook it up to 48 hours later.
How to make it
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- Pre-heat the oven to 190°C/375°F/gas mark 5. Place a pan of lightly salted water on the hob to boil. Peel the potatoes and cut into 3cm² chunks. This will speed up the cooking time. Place them in the pan and simmer for around 10 minutes until soft.
- Place the kale in a steamer and steam over the top of the potatoes for the last 5 minutes.
- Drain the potatoes and mash, add a little milk or butter to soften if you like then leave to one side. Meanwhile, heat the milk in a large pan and add the fish. Bring the milk to a boil then turn down the heat and simmer for 6 - 7 minutes.
- Heat the butter in a large pan and gently fry the leeks for 4 - 5 minutes until soft, but not brown.
- Remove the fish from the pan and set it aside to cool. Pour the milk into a jug. Top tip. Put your milk pan into a bowl of hot water immediately, or it can be a pain to clean if it's like mine!
- Add the flour to the leeks and stir well. Over a low heat, gradually add all the milk, stirring all the time. Season with salt and freshly ground black pepper.
- Carefully break the fish into chunks, leaving behind the skin and stir into the sauce. Add the prawns, peas, kale and lemon zest.
- Place it all in an ovenproof dish, cover with the mashed potatoes using a fork to spread evenly. Start at the edges of the dish and work in towards the middle. Bake in the oven for 25 minutes.

Sustainability
When buying fish look for the Marine Stewardship Council label. This lets you know the fish has been sustainably sourced. Buying sustainably sourced fish is important to protect the long term stocks of different varieties of fish and also to protect the marine environment.

Try to buy vegetables in season and from local sources to minimise the carbon footprint and reduce food miles.
Fish Pie with Leeks and Potato
Ingredients
- 1 kg potatoes organic
- 80 g kale organic, or spinach or cabbage, shredded
- 750 ml milk organic
- 250 g smoked haddock MCS certified
- 200 g white fish fillets MCS certified
- 50 g butter organic
- 360 g leeks organic, washed and sliced
- 3 tablespoon plain flour organic
- 100 g prawns cooked, peeled, defrosted MCS certified
- 100 g frozen peas organic
- 1 lemons organic, fairtrade, zest only
Instructions
- Pre-heat the oven to 190°C/375°F/gas mark 5. Place a pan of lightly salted water on the hob to boil. Peel the potatoes and cut into 3cm² chunks. Place them in the pan and simmer for around 10 minutes until soft.
- Place the kale in a steamer and steam over the top of the potatoes for the last 5 minutes.
- Drain the potatoes and mash, add a little milk or butter to soften if you like then leave to one side. Meanwhile, heat the milk in a large pan and add the fish. Bring the milk to a boil then turn down the heat and simmer for 6 - 7 minutes.
- Heat the butter in a large pan and gently fry the leeks for 4 - 5 minutes until soft, but not brown.
- Remove the fish from the pan and set it aside to cool. Pour the milk into a jug. Top tip. Put your milk pan into a bowl of hot water immediately, or it can be a pain to clean if it's like mine!
- Add the flour to the leeks and stir well. Over a low heat, gradually add all the milk, stirring all the time. Season with salt and freshly ground black pepper.
- Carefully break the fish into chunks, leaving behind the skin and stir into the sauce. Add the prawns, peas, kale and lemon zest.
- Place it all in an ovenproof dish, cover with the mashed potatoes using a fork to spread evenly. Start at the edges of the dish and work in towards the middle. Bake in the oven for 25 minutes.
Notes
Tips
- You can use any fish in a fish pie. Try a combination of white fish and smoked or oily fish. You could also just use one type if you prefer. A fish pie mix is convenient, but buying the fish separately is usually better value.
- Other vegetables you could use include cabbage, spinach, broccoli and sweetcorn.
- The best potatoes to use for mash are Desiree or Maris Piper potatoes in the UK and Russets or Yukon Gold in the US. These are higher starch potatoes and will give a light fluffy mash. Waxy potatoes are more difficult to mash and you can end up with a potato paste rather than fluffy mash. You could also try using sweet potatoes instead or half and half.
- To make sure your mash doesn't sink into the filling, let your cooked potatoes steam for a few minutes. This helps dry them out a little. Watery potatoes weigh heavy and will seep into the filling. When adding the mashed potatoes, use a dessert or tablespoon and spoon it on one spoonful at a time. Start at the edges and work inwards towards the middle. Once you've covered the filling, you can go over the top with a fork to make a pattern or little grooves in the potato that will crisp up nicely in the oven.
Storing and Reheating
- To reheat fish pie, cover with foil and reheat in the oven at 180C/350F/Gas Mark 4 for around 40 minutes until piping hot. To reheat from frozen allow around 1 ½ hours.
- Fish pie can be frozen for up to 3 months. It can be frozen once assembled, without being cooked in the oven. If your fish pie has not already been cooked, leave it uncovered when reheating to allow it to brown on the top.
- It can be stored cooked in the fridge for 2 - 3 days. You can also assemble it up to 48 hours in advance and keep it in the fridge.
Nutrition per serving
The Nutritional Values are computer generated estimates based on industry standards and are provided as a helpful guide only.
Paul
Tasty, colourful and impossible to get wrong! Love this recipe!