Preheat the oven to 350°F (175°C).
In a large mixing bowl, combine the cooked chicken, broccoli florets, uncooked rice, cream of chicken soup, chicken broth, garlic powder, onion powder, salt, and pepper. Mix well until all ingredients are evenly coated.
If using, drizzle olive oil over the mixture for added flavor and moisture.
Transfer the mixture into a greased 9x13 inch baking dish, spreading it evenly.
If desired, sprinkle breadcrumbs over the top for a crunchy texture.
Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes.
After 30 minutes, remove the foil and sprinkle the shredded cheddar cheese on top. Bake uncovered for an additional 10-15 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let it cool for 5 minutes before serving.