Creamy fish pie with cheesy mashed potatoes is a classic comfort food recipe made with flaky salmon, white fish, and juicy prawns in a rich cheddar cheese sauce. Topped with buttery mash and baked until golden, it’s an easy family dinner perfect for weeknights or Sunday meals. This traditional British fish pie is simple to prepare, freezer-friendly, and ideal for feeding a crowd. Great for using fresh or frozen fish fillets, with gluten-free options included. Serve with peas and sweetcorn for a balanced, hearty meal.

A comforting, family-friendly dish packed with flaky fish, succulent prawns, a creamy cheese sauce, and topped with buttery mashed potatoes. This classic British fish pie is perfect for cosy dinners and can be adapted for gluten-free diets.

Ingredients

For the Mashed Potato Topping:

1 kg (2 ½ lb) floury potatoes (like Maris Piper), peeled and cut into large chunks
1 ½ tbsp butter
3 tbsp double cream (heavy cream)
Salt and black pepper, to taste

For the Filling:

600 ml (2 ½ cups) full-fat milk
2 boneless salmon fillets
1–2 boneless cod or haddock fillets
15 king prawns (raw or cooked, deveined)

For the Sauce (Regular Version):

1 ½ tbsp butter
2 tbsp plain (all-purpose) flour
150 g (1 ½ packed cups) mature cheddar cheese, grated
Pinch of black pepper

For the Sauce (Gluten-Free Option):

2 tbsp cornflour mixed with 2 tbsp cold water (to replace flour)

To Serve:

1 tbsp chopped chives
Peas
Sweetcorn

Instructions

1. Preheat the Oven
Preheat your oven to 200°C (400°F), fan-assisted.

2. Prepare the Mashed Potatoes
Place the potatoes in a large saucepan and cover with cold water. Bring to a boil and simmer for 15 minutes until tender.
Drain and mash the potatoes with half of the butter, the double cream, and a pinch of salt and pepper. Set aside.

3. Poach the Fish
Pour the milk into a large saucepan. Add the salmon and cod/haddock fillets. Bring to a gentle boil, then simmer for 2–3 minutes. If using raw prawns, add them for the last minute. The fish should flake easily when done.
Remove the fish and prawns with a slotted spoon, discarding any skin. Flake the fish into large chunks and place with the prawns in a large baking dish. Reserve the poaching milk in a jug.

4. Make the Sauce

Regular Version:
Melt the remaining butter in the same pan. Stir in the flour and cook for 1 minute over medium heat. Gradually add the reserved milk, stirring with a balloon whisk until smooth and thickened. Turn off the heat and stir in half the grated cheese and a pinch of pepper.

Gluten-Free Version:
Return the reserved milk to the pan and heat gently. Stir in the cornflour mixture a little at a time until the sauce thickens. Remove from heat and stir in half the cheese and pepper.

5. Assemble the Pie
Pour the cheese sauce over the fish and prawns in the baking dish.
Spoon the mashed potato on top and spread it out with a fork, creating ridges to help it crisp up.
Sprinkle the remaining cheese over the top.

6. Bake and Serve
Bake in the preheated oven for 15–20 minutes until golden and bubbling.
Sprinkle with chopped chives and serve with peas and sweetcorn.

Tips

Use floury potatoes like Maris Piper or King Edward for a fluffier mash.
Don’t overcook the fish—just a few minutes of poaching is enough.
If using cooked prawns, skip poaching and add them directly to the dish before baking.
For a golden top, grill the pie for a few minutes after baking.

Variations and Substitutions

Fish options: Use smoked haddock for extra flavour or swap salmon for trout.
Cheese: Try Gruyère, Red Leicester, or a cheese blend for a twist.
Add veggies: Mix in cooked leeks, spinach, or peas to the filling.
Topping: Replace mashed potatoes with a sweet potato mash or cauliflower mash for a lighter version.
Dairy-free: Use plant-based butter, cheese, and milk alternatives.

FAQs

Can I make it ahead of time?
Yes. Assemble the pie, cover, and refrigerate for up to 24 hours. Bake when ready to serve, adding an extra 10 minutes if cooking from cold.

Can I freeze fish pie?
Yes, freeze before baking for up to 3 months. Thaw overnight in the fridge before baking.

Can I use frozen fish?
Yes, defrost fully and pat dry before poaching to avoid excess water in the sauce.

Serving Suggestions

Serve with steamed peas, sweetcorn, or green beans. A crisp green salad or roasted carrots also pairs well for a more colourful plate.

Why You’ll Love This Recipe

Comforting and hearty – perfect for chilly nights
Balanced with protein, dairy, and vegetables
Easy to adapt for dietary needs
A family-friendly favourite that reheats well
Rich, cheesy mash topping for a golden, crispy finish