Pre-heat the oven to 200℃
Whilst making the cheese sauce, pop the spinach in a saucepan of salted hot water for a few mins, then drain in a colander. Top Tip : ensure you squeeze as must water out as possible, or you may have a puddle of water at the bottom of your dish.
Spread the spinach at the bottom of a baking dish. Place the haddock on top.
Pour the cheese sauce over the top.
Whizz a slice of bread and parsley in a food processor until you get breadcrumbs. Sprinkle this over the top, place in the oven and cook for around 20-35mins (depending on whether you are using fresh or frozen fish), ensure your haddock is pipping hot throughout.
Serve immediately with some chips/mash and green veg.