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.
