Season the chicken pieces with the black pepper, half the lemon zest, and ½ teaspoon salt, tossing well to coat evenly.
Warm the olive oil in a sizable skillet over medium-high heat, add the chicken, and sauté for about 5 minutes until it develops a light brown crust; then remove and set aside.
Add the diced onion to the skillet and cook for around 3 minutes until it softens, stirring often; then mix in the minced garlic and cook just until its aroma releases, about 30 seconds.
Introduce the orzo to the skillet, stirring continuously as it toasts lightly for 1 minute to enhance flavor.
Pour in the chicken broth along with the remaining salt; put the chicken back into the skillet and bring everything to a boil. Lower the heat to medium-low, cover, and simmer for 8 minutes.
Lift the lid, add the broccoli florets, cover again, and cook for another 3 to 4 minutes until the broccoli is tender-crisp and the orzo is cooked through.
Blend in the butter, lemon juice, Parmesan, and the rest of the lemon zest, stirring until the mixture melts into a creamy consistency; then taste and tweak the seasoning with salt or pepper if needed.
Scoop the finished dish into bowls and sprinkle chopped fresh parsley over the top as a garnish.
