Gratin of haddock, wild mushrooms & potatoes

1. Put the wild mushrooms in a bowl and pour over enough boiling water to cover. Leave to soak for 30-40 minutes. Heat the oven to 200°C, gas mark 6 and put a metal baking tray in to heat up.

2. Heat the olive oil in a frying pan and sauté the chestnut mushrooms over a high heat. You need to cook the mushrooms until they exude all their moisture – you will see this happening – then turn up the heat to drive this moisture off (otherwise your gratin will end up grey and watery). When this has happened, add the butter for flavour. Season.

3. Drain the wild mushrooms (the soaking liquor is good for mushroom soup) and chop any that are large. Cut the fish into slices about 4cm thick. Peel and slice the potatoes very finely – they really need to be wafer thin. It’s best if you do it with a mandolin as it takes much longer working with a knife.

4. Put half the potatoes into a large, shallow, buttered gratin dish – enamel, cast iron or copper work well as they conduct the heat, ceramic ones don’t work as well. Season them as you go and sprinkle with a little nutmeg. Spoon the mushrooms on top.

5. In a saucepan, heat the cream and the garlic to boiling and pour half over the vegetables. Lay the fish on top, followed by the rest of the potatoes, (again, seasoning and sprinkling with a little nutmeg). Pour the rest of the hot cream on top of this and scatter on the cheese. Slide this onto the hot baking tray in the oven and bake for 40-45 minutes, until the potatoes are tender and the surface is golden and bubbling