Blanch the basil leaves in boiling water and then immediately plunge them into iced water for five minutes.
Pat the basil dry and blend it with 100ml olive oil until pureed.
Gently fry the onion and celery in olive oil for five minutes until softened.
Add the garlic, leek, and courgettes to the pan and stir for two minutes.
Add the tomatoes and chicken stock then bring the mixture to a boil.
Stir in the tomato purée and broken spaghetti and cook for eight minutes.
Add the peas, broad beans, and green beans then simmer for five minutes until the pasta is tender.
Season the soup and serve in bowls drizzled with basil oil and topped with parmesan.