directions

1. Place the potatoes in a large pan of cold salted water and bring to the boil. Cover and simmer for about 15 minutes or until tender. Drain well.
2. Return the potatoes to the pan and allow to steam dry for 2-3 minutes. Use a fork to break the potatoes down into rough, chunky pieces. Stir in the olive oil and some salt and pepper.
3. Preheat the oven to 200°C/180˚C fan/gas mark 6 and grease four individual 250ml-capacity ovenproof dishes with butter.
4. Heat the butter and oil in a saucepan over a medium heat. Add the leek and cook, stirring, for 4-5 minutes or until softened slightly.
5. Add the flour and cook, whisking, for two minutes. Whisking continuously, pour in the stock and keep whisking until combined. Cook, stirring, for five minutes or until the mixture comes to the boil.
6. Add the cream cheese and tarragon and cook, stirring, for 2-3 minutes or until the mixture begins to thicken.
7. Add the salmon and prawns and cook, stirring, for 2-3 minutes or until just cooked through. Spoon into the prepared dishes.
8. Gently layer over the crushed potatoes and sprinkle with the Parmesan. Bake for 15-20 minutes or until golden.