Warm the milk in a shallow pan over a low heat. When the milk is steaming, add the haddock and poach gently for 4 to 5 minutes until the fish starts to turn opaque. Remove to a plate or board using a slotted spoon, then transfer the milk into a jug. Set aside. Flake the fish into small pieces, discarding any skin and bones.

Fry the chorizo in a large saucepan over a medium heat for about 5 minutes, until crisp. Remove the chorizo using a slotted spoon and transfer to the plate with the fish.

Add the butter to the chorizo oil left in the large saucepan and melt over a low heat.  Stir in the flour as soon as the butter has melted. Cook for 30 seconds, stirring constantly.

In a separate pan, cook the pasta according to the instructions on the packet. When the pasta is halfway through cooking, turn on the grill to a high heat.

Increase the heat slightly under the large saucepan, then slowly pour the reserved milk into the butter and flour mixture, just a little at a time, stirring well until the sauce is smooth and thickened slightly. Bring it to a gentle simmer, then add 150g of the grated cheese and stir until it has all melted. Add the fish and chorizo to the cheese sauce, stir very gently to combine and cook on the lowest heat while the pasta is cooking.

Once the pasta is cooked, drain and then add it to the cheese sauce mixture.

Stir gently to combine and then transfer to a large serving dish (approx. 35cm x 23cm), top with the remaining grated cheese.

Place under the grill for around 3.5 to 4.5 minutes (until the cheese is bubbling and nicely coloured).