Melt the butter with the oil in a saucepan, add the onion and garlic and cook for about 3 minutes until soft. Add the rice and stir until coated with the butter mixture. Add the wine and cook rapidly, stirring, until it has evaporated.
Add the hot stock, a ladleful at a time, and cook, stirring constantly, until each addition has been absorbed before adding the next. Continue until all the stock has been absorbed and the rice is creamy and cooked but still retains a little bite – this will take around 15 minutes.
Stir in the spinach and courgettes and heat through for 3–5 minutes. Remove from the heat and stir in the Parmesan and herbs. Season to taste with salt and pepper and serve immediately.