- With the rack in the middle position, preheat the oven to 425°F (220°C).
- In a large pot of salted boiling water, cook the pasta until very al dente. Drain and lightly oil. Spread the pasta out on a baking sheet. Set aside.
- Meanwhile, in a skillet over medium-high heat, cook the chorizo in the oil until lightly browned. Drain in a sieve set over a bowl. Set the chorizo and fat aside separately.
- In the same pot over medium heat, melt the butter. Add the flour and cook for 1 minute while whisking. Gradually whisk in the milk. Bring to a boil. Simmer gently for 2 minutes. Remove from the heat. Add the cheddar and mix until melted. Season with salt and pepper. Add the corn, chorizo and pasta. Stir to coat well in the sauce. Transfer into a 13 x 9-inch (33 x 23 cm) baking dish.
- Combine the breadcrumbs and Parmesan with the reserved chorizo cooking fat. Sprinkle over the macaroni.
- Bake for 15 minutes or until the top is golden. Serve with a green salad, if desired.
If you are using fresh chorizo sausage, brown it in the skillet, breaking it up with a wooden spoon.