Prepare the Chicken: Sprinkle ½ teaspoon of the salt, pepper, garlic powder, onion powder, and dried thyme evenly over the chicken, tossing to coat evenly.
Cook the Chicken: Heat a large (5- or 6-quart), heavy bottom pot or Dutch oven (with a lid) over medium-high heat. Add the olive oil and then the chicken in an even layer. Cook until the chicken is browned and just barely cooked through, about 5-7 minutes, stirring occasionally.
Tip: The chicken will continue to cook with the rice, so don’t overdo it here, especially if using chicken breast.
Cook the Onion: Remove the chicken to a plate and set aside. Turn the heat down to medium, and add the butter, onion, and garlic. Sprinkle with ¼ teaspoon of salt, and cook until the onion is softened, stirring occasionally, about 5-6 minutes.
Add the Rice: Add the lemon zest and rice to the onion. Cook until fragrant, about 1-2 minutes, stirring frequently.
Add the Stock: Return the chicken to the pot, along with any accumulated juices. Add the broth and bring to a rapid boil. Cover, reduce to a low simmer, and cook for 15-18 minutes, or until the rice is just tender (it will still have a bit of a bite to it).
Add the Peas: Turn off the heat. Uncover, add the peas, give it a quick fluff with a fork, then quickly re-cover and allow it to sit for an additional 5-8 minutes for the rice to cook fully and the peas to warm through.
Finish: Uncover, and add the lemon juice and Parmesan. Stir with a fork to combine and to fluff the rice.
Testing Tip: Don't lift the lid during the 15-18 minute simmer, no matter how tempting! Every time I peeked, enough steam escaped that the rice cooked unevenly and I ended up with hard grains around the edges.