Preheat your oven to 350°F (175°C).
Grease the casserole dish with olive oil to prevent sticking.
In a mixing bowl, combine the cream of chicken soup, milk, garlic powder, onion powder, salt, and black pepper. Mix well.
Place the uncooked rice on the bottom of the casserole dish.
Layer the mixed vegetables evenly over the rice.
Place the chicken breasts on top of the vegetables.
Pour the soup mixture over the chicken breasts, ensuring they are well coated.
Sprinkle the shredded cheddar cheese on top.
Cover the casserole dish with aluminum foil (if desired) to keep the moisture in.
Bake in the preheated oven for 30 minutes.
Remove the foil and bake for an additional 15 minutes, or until the chicken is cooked through and cheese is bubbly and golden.
Let the casserole sit for about 5 minutes before serving.