01 - Heat olive oil in a large, heavy saucepan or Dutch oven over medium heat. Season diced chicken generously with salt and pepper, then add to the pan. Cook for 5–6 minutes, turning occasionally, until browned on all sides and cooked through. Transfer chicken to a plate and set aside.
02 - Reduce heat to medium-low. Add 1 tablespoon butter to the same pan. When melted, add chopped onion and cook for 3 minutes until translucent and softened. Add minced garlic and stir constantly for 1 minute until fragrant, being careful not to brown.
03 - Increase heat to medium. Add Arborio rice to the pan and stir continuously for 2 minutes. The rice grains should become lightly toasted and develop a slight opaque appearance around the edges.
04 - Pour in the white wine while stirring constantly. Continue stirring until the wine is completely absorbed by the rice and the alcohol smell has evaporated, approximately 1–2 minutes.
05 - Begin adding warm chicken stock one ladleful at a time (approximately ½ cup per addition). Stir frequently, allowing each addition to be absorbed before adding the next. Continue this process for 15 minutes, maintaining a gentle simmer throughout.
06 - Add asparagus pieces to the rice mixture. Continue adding stock ladle by ladle, stirring frequently, for another 10 minutes. The rice should be creamy and al dente with a slight bite in the center, and the asparagus should be just tender-crisp.
07 - Return the cooked chicken to the pan. Remove from heat and stir in the remaining 2 tablespoons butter, Parmesan cheese, and lemon zest. Stir vigorously to emulsify and create a creamy consistency. Taste and adjust seasoning with additional salt and pepper as needed.
08 - Cover the pan and let the risotto rest for 2 minutes to allow flavors to meld. Transfer to serving bowls or plates. Garnish with chopped parsley and additional grated Parmesan cheese if desired. Serve immediately while hot and creamy.