Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the rice, chicken broth, cream of mushroom soup, sour cream, and onion soup mix. Stir until well combined.
Drizzle the bottom of the 9x13-inch baking dish with olive oil to lightly coat.
Spread the rice mixture evenly across the baking dish.
Season the chicken breasts with salt and pepper, and place them on top of the rice mixture.
Cover the baking dish tightly with aluminum foil to keep the moisture in.
Place the dish in the preheated oven and bake for 1 hour and 15 minutes.
After 1 hour and 15 minutes, remove the foil and sprinkle shredded cheddar cheese over the top.
Return the casserole to the oven, uncovered, and bake for an additional 15 minutes or until the chicken is cooked through and the cheese is melted and bubbly.
Remove from the oven and let it sit for 5 minutes before serving. Garnish with fresh parsley if desired.