Cook the pasta according to the pack instructions and drain. Heat a frying pan and cook the chorizo until it’s crisp. Remove from the pan with a slotted spoon onto kitchen roll to drain.
Heat the oven to 200°C/Fan 180°C Fan/ Gas 5. Pour the milk into a pan with the garlic, shallots and bay. Warm gently but don’t boil.
While the milk warms, melt the butter in another saucepan. Add the flour to the pan and stir continuously with a wooden spoon to make a thick, smooth roux.
When the milk is hot but not boiling, strain it, then slowly add it to the roux, whisking until it comes to the boil and thickens. Bubble for 2 minutes then add half the Cheddar cheese and black pepper.
Mix together the sauce, pasta and chorizo and tip into an oven dish. Sprinkle the remaining Cheddar cheese over the top and cook for 25 minutes until golden.