Heat the oven to 180C/160C fan/gas 4. Tip the spinach into a large colander set over the sink and pour over a kettleful of boiling water to wilt. Rinse under cold running water to cool, then squeeze out as much excess liquid as possible.

Butter a medium gratin dish. Roughly chop the spinach, then tip into the prepared dish along with the haddock, cream, lemon juice, parmesan and spring onions. Season with a small pinch of salt, plenty of black pepper and the nutmeg, then stir to combine.

Bake for 15 mins until the mixture is bubbling at the edges and the haddock is starting to flake. Stir again, then smooth the surface. Loosely fold the sheets of filo in concertina-style across the length, then arrange over the pie filling side-by-side so they completely cover the top. Brush over the melted butter and bake for 25 mins more until the pastry is golden and crisp.