Preheat your oven to 350°F (175°C).
In a large skillet, heat olive oil over medium heat. Add the diced chicken and cook until browned and cooked through, about 5-7 minutes.
In a large mixing bowl, combine the cooked rice, cream of mushroom soup, chicken broth, mixed vegetables, garlic powder, onion powder, thyme, salt, and pepper. Stir until well combined.
Add the cooked chicken to the rice mixture and stir to combine.
Transfer the mixture to a greased 9x13 inch baking dish. Spread it out evenly.
Sprinkle the shredded cheddar cheese on top of the casserole.
Cover the dish with aluminum foil and bake in the preheated oven for 25 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden.
Let the casserole cool for a few minutes before serving.