First, preheat oven to 375ºF and spray a large ceramic casserole dish with nonstick cooking spray.
Next, place minute brown rice, broccoli florets, yellow onion, carrots, and green peas on the bottom of the casserole dish.
Prepare cheese sauce by placing broth and milk into a small saucepan. Heat over medium heat.
Once simmering, turn down low/medium and add in 6 oz. shredded cheddar cheese, garlic powder, salt, and pepper. Continuously stir until the cheese melts and your cheese sauce has formed.
Immediately pour over rice and veggies and mix.
Next, slice chicken breasts into 1-inch cubes and add that to the casserole dish and mix making sure everything is fully coated in cheese sauce.
Bake at 375ºF, uncovered, for 30 minutes.
Then, add 2 oz. shredded cheddar cheese and 1 oz. shredded parmesan cheese to the top of the casserole dish and bake for an additional 15-20 minutes.
Let casserole rest on the stovetop for 15-20 minutes before serving to further thicken.