Scrub the potatoes (no need to peel, unless you want to) and chop them into bite-size pieces. Tumble into a pan and fill with cold water, covering the spuds by 2-3cm. Add a generous pinch of salt. Pop on a lid and bring to the boil, then simmer for 15 mins.

While the potatoes come to the boil, trim the roots and top 3cm off the leeks, then cut them in half lengthways and rinse under a cold tap. Thinly slice the leeks. Peel the garlic and crush or finely chop it. Grate the cheddar.

Pour 1 tbsp oil into a large, ovenproof frying pan and warm over a medium heat (if your pan isn't ovenproof, you can transfer to a dish later). Slide in the leeks and garlic with a pinch of salt and pepper. Cook for 5 mins, stirring, till softened.

Add 1 tbsp flour to the leeks and stir well. Cook for a further 2 mins, stirring frequently to stop the flour from catching on the pan.

Add the cheddar and pour in half the pot of double cream. Stir and cook for 1-2 mins, to warm through. Stir in the spinach leaves to wilt them.

Preheat your grill to medium-high. Nestle the haddock fillets into the pan with the veg. Season with salt and pepper and slide under the grill. Cook for 7-8 mins, till the fish is cooked through and flakes easily when pressed with a fork. If your frying pan isn’t ovenproof, pour the creamy veg into a heatproof dish, tuck in the fish and grill.

While the fish cooks, chop the thyme leaves. Pull any ragged leaves off the Brussels sprouts and halve or quarter any larger sprouts. The potatoes should be almost cooked. Add the Brussels and cook for 2-3 mins, till the sprouts are just tender and the spuds are ready. Drain and tip into a bowl.

Pour 1 tbsp oil over the potatoes and sprouts. Add the thyme leaves. Squeeze over the juice from the lemon and season. Gently stir to coat.

Serve the grilled haddock with the creamy veg, and the thyme and lemon potatoes and Brussels sprouts on the side.