Step 1

Sprinkle salt all over each fish fillet and leave in the fridge for 30 minutes. Meanwhile, to make the sauce, melt the butter in a saucepan with the shallot and fry gently, until soft but not coloured. Stir in the flour until the flour and butter bind together and the mixture smells nutty, but isn’t browned.

Step 2

Remove the pan from the heat and add the milk, in small amounts at first, stirring continuously. Return the pan to the heat and keep stirring until the sauce comes to just under the boil. Stir in the fish stock and cream, then allow the sauce to simmer for about 20 minutes (it thickens as it cooks) stirring occasionally. Cover with a lid until the fish is cooked.

Step 3

At the same time as you make the parsley sauce, put the carrots in a saucepan and add enough boiling water to cover, then season and add the butter. Bring to the boil, then turn down to a simmer. Cook until the carrots are tender and the water has almost disappeared. Add a good pinch of sugar and shake the pan as the rest of the liquid reduces and the carrots become sweet and buttery. Put a lid on to keep them warm. Preheat the oven to 200ºC, gas mark 6.

Step 4

Rinse the fish in water, then pat it dry. Brush a small roasting tin or gratin dish with the oil. Lay the fillets on top and brush them with oil. Bake in the oven for 12-15 minutes (the exact timing depends on the thickness of the fillets you use), until the cod is opaque and cooked through.

Step 5

Warm the sauce again, add a generous squeeze of lemon juice and stir in the parsley. Check the seasoning. Quickly reheat the carrots, then put a fillet of fish on each of 4 warmed plates and spoon over the sauce. Serve the remaining sauce in a warm jug with the carrots.