This is such an easy soup to make. The basil gives it a lovely pungent flavour but you could also use mint to give a fresher flavour.
Heat a generous amount of olive oil in a large pan and add the onion, celery, carrot and garlic. Cover and cook over a low heat, stirring frequently, for 30-40 minutes.
Add the peas and the stock and bring to the boil. Reduce the heat and simmer for about 10 minutes. Add the basil and remove from the heat. Use a stick blender to whizz to a smooth soup. Add salt and pepper to taste. Serve with the parmesan shavings on top and a drizzle of your best olive oil. Great served with crusty bread.