Step 2

Put the potatoes into a saucepan of cold salted water. Bring to the boil and simmer until completely tender. Drain well and mash with the butter and milk. Season with pepper, taste and adjust.

Step 3

Melt the 75g butter in a saucepan, add the leeks and stir over the heat. Cover with a lid and simmer gently for 10 minutes, or until soft.

Step 4

Measure the flour into a small bowl, add the wine and whisk together until smooth.

Step 5

Add the milk to the leeks and bring to the boil, then add the wine mixture. Stir briskly until thickened. Season and add the parsley and fish. Stir over the heat for 2 minutes, then spoon into an ovenproof casserole. Scatter over the eggs and allow to cool until firm.

Step 6

Spoon the mashed potatoes over the fish mixture and mark with a fork. Sprinkle with the grated Gruyère.

Step 7

Bake for 30–40 minutes, or until lightly golden-brown on top and bubbling around the edges.