Preheat the oven to 375°F and lightly grease a 9x13 baking dish.
Heat the olive oil in a large skillet over medium heat. Cut the chicken thighs into bite-size pieces, season with salt, pepper, and garlic powder, then cook until no longer pink, about 6 to 7 minutes. Remove from heat.
In a mixing bowl, stir together the cream of chicken soup, milk, and 1 cup of the shredded cheddar until smooth.
Add the uncooked rice, frozen broccoli florets, and cooked chicken to the bowl. Stir until everything is evenly coated.
Pour the mixture into the prepared baking dish and spread it into an even layer. Sprinkle the remaining 1 cup of cheddar over the top.
Cover tightly with foil and bake for 35 minutes. Remove the foil and bake 10 minutes more until the cheese is melted and the rice is tender.