Heat the oil in a non-stick pan then pinch in nuggets of the sausage and fry until browned all over, breaking up the sausage into smaller nuggets as you fry. Add the garlic, fennel seeds, smoked paprika and chilli flakes, and cook for 2 minutes. Tip in the tomatoes, tomato purée and stock, and bring to a simmer. Stir in the pasta, put on a lid and cook on a gentle simmer for 12-15 minutes, stirring now and again. When the pasta is almost cooked, stir in the cheeses and basil, and leave to sit off the heat for 2 minutes. Serve in warm bowls with extra parmesan, if you like.