Smoked fish pie with butterbean mash

Method

1. Heat the oven to 180ºC fan/gas 6. Pour 300ml of the milk into the ovenproof dish and add the white fish. Bake for 7-8 minutes or until almost cooked. Set the fish aside on a plate to cool, leaving the milk in the dish.

2. Melt half the butter in a pan over a low-medium heat. Add the flour and mix well to make a paste. Gradually add the milk you used to cook the fish, beating in well after each addition to avoid lumps, then add another 300ml milk and mix well. Turn the heat to medium-high and bring to the boil. Simmer for 3-4 minutes until the mixture has thickened to a custard-like consistency. Season well, then add about a third of the lemon juice with the herbs, watercress and, if using, capers. Pour into the dish, then flake in the white fish and smoked trout, discarding any skin.

3. Put the beans, remaining milk, butter, lemon juice and some salt and pepper in a food processor and whizz until smooth. Spread over the fish mixture and bake for 30-40 minutes until golden.

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