01 - Heat the olive oil and 1 tablespoon butter in a large saucepan over medium heat. Add the onion and cook until translucent, about 3 minutes. Add the garlic and cook for 30 seconds.
02 - Stir in the arborio rice and cook for 2 minutes, until the rice is lightly toasted.
03 - Pour in the white wine and stir until absorbed.
04 - Add the warm vegetable broth, one ladle at a time, stirring frequently and allowing each addition to be mostly absorbed before adding the next.
05 - After 10 minutes of cooking, add the asparagus pieces. Continue adding broth and stirring.
06 - When the rice is just tender and creamy (about 18–20 minutes total), stir in the peas, lemon zest, remaining butter, Parmesan cheese, and, if using, heavy cream. Cook for 2–3 minutes more, until the 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.
08 - Serve hot, garnished with fresh parsley and extra Parmesan if desired.