01 - Heat olive oil and 1 tablespoon butter in a large saucepan over medium heat. Add onion and cook until translucent, about 3 minutes. Add garlic and cook for 30 seconds until fragrant.
02 - Stir arborio rice into pan and cook for 2 minutes, stirring constantly, until rice grains are lightly toasted and edges become translucent.
03 - Pour in white wine and stir continuously until completely absorbed by rice, about 1 minute.
04 - Add warm vegetable broth one ladle at a time, stirring frequently. Allow each addition to be mostly absorbed before adding more. Continue for 10 minutes.
05 - Add asparagus pieces to risotto. Continue adding broth ladle by ladle and stirring frequently for another 8-10 minutes.
06 - When rice is tender and creamy (about 18-20 minutes total cooking), stir in peas, lemon zest, remaining butter, Parmesan cheese, and heavy cream if using. Cook 2-3 minutes until peas are bright green and heated through.
07 - Season with salt and pepper to taste. Remove from heat, cover, and let rest for 2 minutes to allow flavors to meld.
08 - Serve hot, garnished with fresh parsley and additional Parmesan cheese if desired.