Preheat the oven to 400 degrees F (200 degrees C). Spray a deep 9x13-inch (or larger) baking dish with cooking spray.

Mix chicken stock, condensed soups, melted butter, salt, and pepper together in a large bowl until well combined. Set aside.

Spread rice on the bottom of the prepared baking dish. Top with cubed chicken. Carefully pour stock-soup mixture over the top, being careful it doesn’t overflow. Sprinkle with Cheddar cheese to cover.

Bake in the preheated oven until chicken is cooked through and cheese is nicely browned, 60 to 75 minutes, depending on the size of chicken cubes. An instant-read thermometer inserted into the center of meat should read at least 165 degrees F (74 degrees C). Remove from the oven and let cool for about 10 minutes before serving.