Cook the chicken. Heat the olive oil in a large, deep skillet over medium heat. Add the chicken and season with ½ teaspoon of the salt and ¼ teaspoon of the pepper. Cook for 3–4 minutes, stirring occasionally, until the chicken is browned on the outside but not cooked through.
Sauté the aromatics. Add the butter, diced onion, and garlic. Cook for 2–3 minutes, stirring occasionally, until the onion begins to soften and the garlic is fragrant.
Add the rice and seasonings. Stir in the uncooked, washed rice, remaining ½ teaspoon salt, remaining ¼ teaspoon pepper, paprika, and garlic powder until everything is well combined.
Cook the rice. Pour in the chicken broth and increase the heat to bring the mixture to a boil. Once boiling, reduce the heat to medium-low, cover, and gently simmer for 8 minutes.
Add the broccoli. Stir in the broccoli florets, cover, and continue cooking for 8–10 minutes, or until the rice is tender, the liquid has been absorbed, and the broccoli is tender-crisp. If the rice needs a little more time, cover and continue cooking for a few additional minutes.
Make it creamy. Reduce the heat to low. Stir in the Dijon mustard, Greek yogurt, 1½ cups shredded cheddar, and Parmesan until the cheese is melted and the mixture is creamy.
Finish with cheese. Sprinkle the additional ⅓ cup cheddar evenly over the top. Cover the skillet for 1–2 minutes, or until the cheese is melted.
Serve. Garnish with fresh parsley, if desired, and serve warm.