Heat the oil in a large, heavy-based saucepan. Add the onion and cook for 5 minutes until softened. Add the garlic and rice and cook for 30 seconds until coated in the oil. Pour in the wine and bubble until boiled away.
Gradually add the stock, a ladleful at a time, stirring continuously and allowing each ladleful to be absorbed before adding the next. After 10 minutes, add the asparagus, then cook for a further 5 minutes until the rice is tender.
Stir in the peas and butter, cover and leave to stand for 1–2 minutes. Season the risotto taste, then spoon into warmed bowls and top each portion with a handful of rocket and some Parmesan shavings.