Pour the stock into a saucepan, bring it to the boil, then reduce the heat to low and leave it gently simmering.
Heat the extra virgin olive oil in a heavy-based saucepan. Add the onion and sauté on a medium heat until softened but not coloured. Stir in the rice with a wooden spoon and coat each grain with the oil.
Add the wine and allow to evaporate, stirring all the time. Stir in the courgette, asparagus and peas. Add a couple of ladles of hot stock and, stirring continuously, cook until the stock is absorbed.
Add more stock and repeat. Continue adding stock, cooking and stirring in this way for about 20 minutes, until the rice is cooked. It should be soft on the outside but al dente on the inside.
Remove from the heat and beat in the butter and parmesan with a wooden spoon. Leave to rest for one minute, then serve.
To make Parmesan crisps, place 4 dessertspoons of coarsely grated Parmesan on a line baking sheet. Sprinkle with black pepper and bake in the oven at 180c/200c/gas 6 until flattened and golden. They will crisp as they cool.
