Fish Fight

1 Preheat the oven to 200C/gas 6.

2 Put a large pan over a high heat and add the wine, 2 tablespoons of water and the diced shallot. Bring to a simmer, then throw in the mussels and cover with the lid.

3 Let the mussels steam open in the pan for 3-4 minutes, shaking once or twice. Remove from the pan with a slotted spoon (discarding any that remain firmly shut) and set aside until cool enough to handle.

4 Pick the mussels from their shells and set aside. Strain all the cooking liquor through a fine sieve or a coarse sieve lined with a cloth.

5 Heat the oil in a frying pan, add the bacon and sauté gently until starting to crisp up. Add the garlic and cook for a further minute or so, being careful not to let the garlic burn. Transfer to a bowl.

6 Now make the béchamel sauce. Combine the reserved mussel cooking liquor with enough milk to make 500ml and heat gently in a pan.

7 Melt the butter in a separate pan. When foaming, add the flour and stir to make a smooth roux. Gradually add the warmed milk, stirring well after each addition to prevent lumps. Simmer gently for 4-5 minutes.

8 Drop the spinach into a large pan of boiling water and cook for just a minute, until wilted. Drain, leave to cool a little, then squeeze out excess water with your hands. Chop the spinach roughly.

9 Fold the bacon, mussels and spinach into the béchamel sauce. Season with freshly ground black pepper and a squeeze of lemon juice.

10 Divide the mixture between four buttered, shallow ovenproof dishes or spread in one large gratin dish. Sprinkle over the breadcrumbs, plus the cheese if using, and trickle over a little rapeseed or olive oil.

11 Bake for 10-12 minutes, until golden and bubbling. Serve hot, with bread.