Preheat your oven to 180 °C (350 °F). In a large bowl, combine cubed chicken, uncooked rice, chicken broth, cream of chicken soup, sour cream, onion powder, garlic powder, salt, and pepper. Stir until all ingredients are evenly distributed. The base should be creamy but still pourable, which helps cook the rice evenly in the oven.

Lightly spray or grease a 9×13-inch baking dish, then spread half of the fresh broccoli florets evenly across the bottom. Pour the chicken and rice mixture over the broccoli, gently spreading it so everything is coated and level. If some broccoli sits on top, that’s perfectly fine — it will roast as the casserole bakes.

Sprinkle one cup of the shredded cheddar cheese evenly over the top of the casserole. This first layer of cheese will melt into the creamy sauce and help bind the ingredients together. Cover the dish with foil and bake in the preheated oven for 30 minutes to allow the rice to absorb liquid and the chicken to cook through.

Remove the foil and sprinkle the remaining shredded cheddar cheese on top. Add the rest of the broccoli if desired for extra color and texture. Return the dish to the oven and bake uncovered for another 15–20 minutes, or until the cheese is golden and bubbly and the rice is tender. Let rest for 5 minutes before serving.