1Bring stock to the boil in a saucepan over medium heat. Reduce heat to low-medium. Cover. Keep at a gentle simmer. Heat oil and half the butter in a large saucepan over medium heat. Add onion and garlic, then cook, stirring, for 4-5 minutes or until onion is soft.
Add rice. Cook, stirring, for 2 minutes or until rice is hot and well coated in onion mixture.
Add 1 cup hot stock and stir continuously until stock has been absorbed. Add another cup of stock. Stir until stock has been absorbed.
Add asparagus to pan. Continue to add remaining stock, a cupful at a time, stirring continuously, allowing stock to be absorbed before adding more, until mixture is creamy and rice is just tender (this should take about 20 minutes) but still al dente; add a little extra stock or water if necessary. Prepare SlimPasta and cut finely. Add SlimPasta to mixture.
Add lemon rind, juice, remaining butter, prosciutto and parmesan to risotto. Stir to combine. Season to taste with salt and pepper. Serve immediately.