To make the chorizo mixture, heat the extra virgin olive oil in a large non-stick frying pan over a medium heat. Add the onion, garlic and peppers with the 1 tsp of salt. Cook, stirring, for 8 to 10 minutes until the vegetables have softened. Add the chorizo and cook, stirring, for 8 to 10 minutes until it releases its fat. Add the tomato puree and paprika, stir for 2 minutes, then add the tomatoes and cook, simmering, for 15 minutes until thickened and reduced. Season to taste.

For the cheese sauce, put the butter in a saucepan over a low to medium heat and stir until melted. Add the flour, garlic powder, onion granules and cayenne and cook for 2 minutes. Add the milk in 2 batches, whisking to to make sure there are no lumps. Whisk in the sour cream. Turn the heat up to medium and bring to a simmer. Cook for 5 minutes or until slightly thickened. Remove from the heat and stir in half the cheese and season, to taste.

Heat the oven to 200C/180C fan/gas mark 6. Scatter the tortilla chips over a baking tray or ovenproof serving dish, then spoon over the chorizo mixture, followed by the cheese sauce. Scatter over the remaining 50g of grated cheese and bake for 20 to 25 minutes or until golden and bubbling. Serve immediately.