Put a large saucepan on a medium heat and add the butter, onion, garlic and chilli, then let it all sweat off for a good eight to ten minutes until everything is nice and soft and very sweet. Make sure you keep stirring so nothing burns.
Crumble in the stock cube along with plenty of black pepper, and fry off for another minute before adding the flour. Cook for a minute or two to make a roux, then slowly add the milk, whisking all the time as you don’t want it to be lumpy.
Cook on a low heat until the sauce has thickened, then take it off the heat and add the grated cheese. Stir until the cheese has melted into the sauce, add your parsley and season.
Put a large pan filled with water on a high heat and bring to the boil. Cook the macaroni for six to seven minutes – it will keep cooking after you drain it so you want it to be al dente – and drain in a colander.
Heat a small frying pan and add the chopped chorizo – you don’t need to add any oil as the chorizo will release plenty as it heats up. You want to get it nice and crispy so fry it off for a few minutes on a high heat, stirring and reducing the heat if it starts to burn.Keep a few pieces of chorizo aside to garnish your dish at the end.
Add the smoked haddock and the peas to the remaining chorizo in the frying pan and cook until the haddock starts to flake. Stir the contents of the pan into the cheese sauce and mix in the pasta. You might need to give everything another quick blast of heat. Garnish with the reserved chorizo pieces and a sprinkle of chopped chives and serve.