Meanwhile, cook the pasta in a pan of boiling salted water for 6-8 mins or until al dente. Heat the oven to 200C/180C fan/gas 6. Drain the pasta, reserving some of the water, and tip into the chorizo sauce. Stir well, adding a splash of the reserved water (about 75ml) to loosen the sauce enough to coat the pasta, if needed. Transfer the mixture to a large baking dish (ours was 20cm x 30cm) and dot over the mozzarella. Bake for 20-25 mins or until golden and bubbling. Leave to stand for 5 mins before serving.