Fish Pie with Butter Bean Mash

It feels like comfort food season has well and truly arrived. I love all the British classics - shepherd's pie, bangers and mash, toad in the hole - but there's just something extra comforting about a good fish pie. I think it might be the white sauce which just hugs you from the inside out. Heaven.

This version uses butter beans in the mash instead of the usual potato, something I picked up from this month's copy of Delicious. It works really well because it's sort of sturdy and holds its shape better which means it gets a properly crispy top and provides contrast to the velvety deliciousness below. I also added a variety of fresh herbs (tarragon or dill would also work well) as well as peppery watercress which really boosts the flavour.

Fish Pie with Butter Bean Mash
Serves 4

650ml whole milk

4 skinless white fish fillets (I used cod)

60g unsalted butter, room temperature

30g flour

3 handfuls fresh herbs, chopped (I used basil, parsley and chives)

50g watercress, roughly chopped

2 tbsp capers, drained and chopped (optional)

2 x 400g tins butter beans, drained and rinsed

1 lemon, juice only

150g hot smoked salmon or trout

sea salt and freshly ground black pepper

Preheat the oven to 180C fan/gas 6.

Pour 300ml of the milk into an ovenproof baking dish (approx. 2L), season well with salt and pepper then lay in the white fish fillets. Bake in the preheated oven for 7 minutes. The fish should be barely cooked. Remove the fish to a plate with a slotted spoon, reserving the milk.

Heat a saucepan over a low heat and add 30g of the butter. Once melted, add the flour and whisk until you have a thick paste. Add the milk used for cooking the fish slowly, whisking between each addition. Then add 300ml more milk, again continuing to add slowly and whisking continuously. 

Turn the heat up and bring to the boil, reduce to a simmer and cook for around 5 minutes, stirring, until the sauce had thickened to a custard-like consistency. It should coat the back of a spoon.

Remove from the heat and add the herbs, watercress, capers (if using) and a third of the lemon juice. Taste and adjust the seasoning - don't be shy with the black pepper. Pour into the baking dish then flake over the white fish discarding any bones. Next flake over the hot smoked salmon/trout.

Blitz the beans in a food processor with the remaining 50ml milk, 30g butter, lemon juice and plenty of salt and pepper. Spoon small dollops of this mixture on top of the fish then carefully spread out - I find a palette knife or a clean finger works well.

Bake the pie in the oven for 30-40 minutes until browned on top. Serve with whatever veg you like but buttered peas are best.