Heat the oil in a heavy-based pan over a medium heat.
Cook the garlic, basil, salt and courgette slowly for 10 minutes, or until the courgettes are lightly browned and softened.
Add white pepper, to taste, then pour in the stock and simmer for 8 minutes, uncovered. Remove from the heat.
Put three-quarters of the soup mixture into a food processor and blend until smooth.
Return the mixture to the pan and stir in the cream, parsley and parmesan.
To serve, ladle the soup into a bowl and season, to taste, with salt and freshly ground black pepper. Sprinkle over more parmesan, to taste. Serve with crusty bread and a green salad.