Preheat your oven to 350°F and grease a 9x13-inch baking dish.
In a large bowl, whisk together the uncooked rice, both cans of soup, chicken broth, and Montreal steak seasoning until well mixed. Pour this mixture into your prepared baking dish and spread it evenly across the bottom.
Nestle the pieces of chicken on top of the rice mixture without stirring it in.
Evenly distribute thin slices of butter over the top of the chicken.
Cover the baking dish tightly with aluminum foil and bake for about 55 minutes.
After 55 minutes, uncover your dish and continue baking for an additional 10–15 minutes until the chicken reaches an internal temperature of at least 165°F and the rice is tender.
Once done, let your casserole sit lightly covered with foil for about 10 minutes before serving.
For an added touch, return your casserole under the broiler for just a couple of minutes until golden brown on top.