Set your oven to 200°C (400°F) and lightly grease a 23×33 cm (9×13 inch) baking dish.
Rinse the rice under cool running water until the water is mostly clear. Transfer the rice to the prepared dish, then add the chopped onion, half of the minced garlic, 2 cups of broth, 1 tablespoon of olive oil, 1/2 teaspoon of salt, and a pinch of pepper. Stir everything together to combine.
In a small bowl, mix 2 tablespoons of olive oil with the lemon zest, lemon juice, remaining garlic, oregano, thyme, smoked paprika, and 1/2 teaspoon of salt. Whisk until well blended.
Pat the chicken dry, coat each piece evenly in the lemon-herb mixture, and arrange them over the rice mixture.
Cover the dish tightly with foil and bake for 30 minutes.
Remove the foil, gently stir the rice around the edges, and sprinkle peas on top if desired. Return the dish to the oven, uncovered, and bake for 15–20 minutes more, until the chicken is cooked through and the rice has absorbed most of the liquid.
Allow the dish to rest for 5–10 minutes before serving. Fluff the rice with a fork, add a sprinkle of parsley, and serve warm.