Heat the olive oil in a pan and cook the onion slowly until softened and deep gold. Add the garlic, courgette and pepper and cook for a further five minutes until softened. Stir in the tomato purée and cook out for two minutes.
Pour in the chopped tomatoes and stock and bring to the boil. Season. Add the pasta and bay leaf and cook according to packet instructions, although the pasta may take a minute or two longer – just keep testing.
Remove and discard the bay leaf, adjust the seasoning if necessary. Serve with grated Parmesan.