1. Pour the stock into a large saucepan and bring to a simmer. Heat the olive oil and butter in a large pan or saucepan, then add the onion and garlic. Stir for 3 minutes.   
2. Add the rice and continue stirring for a further 2-3 minutes until the grains are covered with the oil and butter. Add a ladle full of stock and stir until it has absorbed into the rice, then repeat.
3. After adding half the stock, add the asparagus and mushrooms. Stir through the basil leaves, then continue adding the stock until the rice is creamy and tender.
4. Season to taste and stir through the pecorino before serving in warmed bowls topped with remaining basil leaves.

*If not using home-made stock, it can be a good idea to use two thirds commercial stock and one third water because some stocks can be too salty.