Bring the stock to a boil in a large pan, then lower heat to keep it hot.
Heat 30g butter in a wide pan and sauté the onion until foaming.
Grate 200g of courgettes and fry with the onion until tender.
Sauté 400g of cubed courgettes in 15g butter and oil in a separate pan until brown.
Stir the rice into the onion and grated courgette mixture for one minute until translucent.
Add white wine and simmer until fully absorbed.
Finely chop all fresh herbs.
Add stock one ladle at a time, stirring until absorbed, until rice is al dente.
Stir in sautéed courgettes and most herbs, heating for two minutes.
Stir in remaining 15g butter and parmesan, then season and serve with remaining herbs.