The saltiness and sharp taste of cheese make this soup a delicious appetizer. Served with parmesan crisps makes it a show-stopper. So comforting, so delicious.
In a large pot, put the butter and oil over medium-high heat. Add the onion and garlic and cook, stirring, until onion is soft and lightly coloured. Add the courgettes and give everything a good stir. Add the basil leaves and pour in the water or broth. Cover the pot and bring to boil. Lower the heat and simmer, 15 minutes until courgettes are cooked.
Transfer mixture to a blender. Blend on high speed until everything is pureed and smooth. Transfer soup back to the pot, over medium heat. Add the parmesan cheese and the gruyere. Heat through until cheeses have melted. Season with salt and pepper. Taste the soup and adjust seasoning.
Serve warm, drizzled with the pesto oil, pine nuts and parmesan crisps