Heat oil in a large frying pan over medium heat. Cook garlic and brown onion, stirring, for 5 minutes or until softened.
Add stock and cream, then bring to the boil over high heat. Add rice, asparagus and snow peas. Reduce heat to medium and cook, stirring, for 4 minutes or until rice is heated through, and asparagus and snow peas are just tender.
Stir in peas and two-thirds each of the spring onion and parmesan. Cook, stirring, for 2 minutes or until peas are tender. Add butter and stir until melted. Season with pepper. Serve risotto topped with remaining spring onion and parmesan, and lemon wedges.