This recipe was designed with family eating in mind.
However, it is so good that you could easily serve it at a supper party. You may need to skin the fish, but don't let that deter you: it's much simpler than it sounds.
This recipe first appeared in Sainsbury's the Magazine 1996 Serves 4
If you need to skin the haddock, this is how to do it.
All you need is a flat surface and sharp knife. Angle the knife at the tail of the fillet, then cut a little flesh away from the skin – just enough to get the knife angled in. Now hang on to the skin with your fingers, pressing as firmly as possible, then push the knife with your other hand (keeping the blade at an angle), pushing at the skin rather than the flesh; the skin is very tough and the knife won't go through it. Continue like this until the fillet has come away from the skin.
Next, cook the spinach according to the instructions on the pack, then transfer the spinach to a colander until cool enough to handle.
Meanwhile, prepare the breadcrumbs by dropping the bread into a processor with the parsley. Next, run your fingertips over the surface of the skinned fish and remove any stray bones with tweezers, then pat the fish dry with kitchen paper. Return to the spinach and squeeze it in your hands very tightly to get rid of every last drop of water – you need to get it as dry as possible.
Then place it on a clean board and chop it finely. Mix the chives with the four-cheese sauce and add 2 tablespoons of the sauce to the spinach, season it with salt, black pepper and nutmeg, then arrange it in the dish.
Next, place the fish on top of the spinach and season again, scatter the mozzarella over the surface, then spoon the rest of the sauce evenly over the fish, using a spatula to spread it to the corners. Now mix the Parmesan with the breadcrumbs and parsley and scatter this over the sauce.
Next place the dish in a pre-heated oven, one shelf above centre, and bake for 25-30 minutes, or until the top is golden.
Check the fish is cooked by placing a knife and fork into the thickest part of the fillets and gently pulling them apart. If it's ready, allow everything to settle for 4-5 minutes before serving.