Preheat the oven to 375 degrees. Place a large deep skillet on the stove over medium high heat. Add the broccoli and 1/2 cup water to the pan. Cook the broccoli, stirring occasionally, until cooked through and crisp tender, about 4-5 minutes.Season with salt and pepper to taste. Remove the broccoli from the pan and set aside; remove any excess water from the pan. Heat the oil in the pan over medium high heat. Season the chicken thighs on both sides with salt and pepper to taste. Place the chicken in the pan, skin side down, and cook until the chicken is a deep golden brown, about 5-7 minutes. Flip the chicken and repeat the process with the other side. Remove the chicken from the pan and add the onion. Cook for 4-5 minutes or until onion is translucent. Add the rice, cooking for 1 minute. Place the chicken back into the pan. Pour in the chicken broth and season with 1/2 teaspoon salt and 1/4 teaspoon pepper. Bring the mixture to a boil. Cover the pan and place it in the oven. Bake for 35 minutes or until liquid has absorbed and chicken is cooked through. Remove the pan from the oven and place the chicken on a serving plate, cover with foil. Stir the broccoli and cheese into the rice mixture and place it back in the oven. Cook for 5 more minutes or until cheese is melted. Place the broccoli cheddar rice on the platter alongside the chicken. Garnish with parsley (optional) and serve.