Prepare and trim asparagus*. Cut stalks into 2 cm long pieces, reserve the tips.
Place ⅔ of stalk pieces, 1 cup broth and 1 cup water in blender and puree until almost smooth. Set aside.
Sauté onion in olive oil and 1 tablespoon butter for 5 minutes in a large pan, over medium heat.
Add prosciutto and sauté for 3 more minutes.
Add rice and stir to coat the grains for 2 minutes. Add wine and cook until absorbed, stirring often, about 2 minutes.
Add ½ cup stock and simmer until liquid is absorbed, stirring often, about 4 minutes. Continue to cook for 15 minutes, adding more stock as needed and allowing liquid to be absorbed before adding more, stirring often.
Add remaining asparagus stalk pieces and reserved asparagus tips and continue cooking until rice is just tender and mixture is creamy, adding stock as needed and stirring often, about 10 minutes longer.
Add reserved asparagus puree and stir until absorbed, about 3 minutes.
Stir in the remaining butter, Parmesan and cream but do not return to the heat.
* Slightly bend each stalk and allow it to „snap“ naturally – it will break exactly at the point where the stalk begins to be thick and woody. Remove these hard parts.