Heat the oven to 200°C/fan oven 180°C/mark 6. In a heavy-based saucepan frying pan, melt the butter and add the leeks with a pinch of salt. Add a splash of water and then cover, sweating the leeks until they are soft and melting, about 20 mins. Check intermittently so that the leeks aren’t burning at the base of the pan.

Add the cream (or creme fraiche, if using), bay leaf, beans and spinach to the leeks and stir to combine. Bring to a boil, then reduce to a simmer. Then, add the smoked haddock and stir into the sauce, being careful not to break up the chunks too much. Simmer away for 10-12 minutes. If it’s looking too thick, add the reserved bean stock. Season generously with black pepper, but go easy on the salt as the fish and beans already are salted.

Pour the mixture into a large, shallow oven-proof dish. Cover the mixture with the cheese and breadcrumbs.

Bake in the oven for 25-30 minutes, until the gratin is tender and the fish is just flaking.

Whilst the pie is baking, blanch the peas and green beans in boiling water for a few minutes. Drain and stir through the butter and chopped mint.

Once the pie is bubbling and golden, serve immediately with the minty greens.