Preheat the oven to 200C/Gas6; place the smoked haddock in a shallow pan, cover with the milk and add the bay leaves and seasoning; bring to the boil and simmer gently uncovered for 6 minutes; lift the smoked haddock out to a plate and break up into chunky pieces; strain the milk into a jug
Cook the spinach in the microwave; cook the macaroni for 5-6 minutes, then drain and rinse in cold water; squeeze out the excess moisture from the spinach and chop roughly
For the cheese sauce, place the cornflour in a saucepan and gradually blend in the reserved milk; heat, stirring, until the sauce thickens, then simmer for 2 minutes; combine the cheeses and stir three-quarters into the sauce, along with the mustard and season to taste; stir the drained macaroni into the cheese sauce
Scatter the smoked haddock over the base of an ovenproof dish then add the spinach; spoon the macaroni cheese over the top; finally top with sliced tomato, then mix the rest of the cheese and the chives together and sprinkle over the surface
Bake in the oven for 20-25 minutes until the sauce is bubbling and the top is golden
4 servings