Preheat the oven to 180°C fan/200°C/400°F/Gas Mark 6.

In a bowl, toss the potatoes and the sweet potatoes with the oil and thyme. Season, then spread out on a baking tray and roast in the top of the oven for about 15 minutes until lightly coloured and still retaining a slight bite. Remove from the oven and place to one side. Reduce the oven temperature to 170°C fan/190°C/375°F/Gas Mark 5.

Add the milk and bay leaves to a large nonstick frying pan. Add the smoked haddock, skin-side down, cover and bring to a gentle simmer over a medium heat. Cook for 4–5 minutes until the fish is opaque and starting to flake into pieces. Turn the heat off and leave the fish to stand in the milk for 5 minutes. Lift the fish onto a plate, flake into large pieces and place in a 20 × 25cm (8 × 10 inch) baking dish. Strain the poaching milk into a jug and place to one side.

Wipe the frying pan clean and add the bacon lardons. Put the pan on a medium–high heat. Cook for 10–15 minutes until brown and crisp, then carefully remove the bacon from the pan using a slotted spoon so that the fat stays in the pan. Place the bacon onto kitchen paper to absorb any excess fat and oil, then scatter on top of the flaked haddock. Add the onion and chilli to the pan with the rendered bacon fat. Cook on a medium heat for 3–4 minutes until the onions are soft and translucent. Transfer to a plate and place to one side.

Wipe the frying pan clean again and add the butter. When it’s melted, stir in the flour and cook for 1 minute over a medium heat. Take off the heat, pour in a little of the poaching milk, then stir until smooth. Continue to add the milk gradually, mixing well, until you have a smooth sauce. Stir in the cream and lemon zest, followed by the onions and chilli. Cook over a low heat for 2 minutes, stirring continuously. Season to taste and remove from the heat.

Add the sweetcorn and broccoli to the haddock and bacon, cover with the sauce, then spread the potatoes and sweet potatoes in an even layer on top. Sprinkle over the Cheddar and paprika. Bake in the oven for 20 minutes, until golden and bubbling around the edges.

Serve with buttered garden peas and lots of crusty bread to mop up the sauce. Add some spicy sauce – like sriracha or Tabasco – to the table, for folks who like things hot.