This casserole is a favorite in our test kitchen and it's easy to see why. It's delicious, family friendly and easy to prep. You might want to double this recipe—you're going to want leftovers.
Position oven rack 8 inches from heat source. Preheat oven to 375°F. Sprinkle chicken with pepper and 3/4 teaspoon of the salt. Heat oil in a large skillet over medium-high. Add chicken; cook, stirring once, until well browned, 5 to 6 minutes. (Chicken will still be raw at this point.) Transfer chicken to an 8- x 8-inch baking dish coated with cooking spray.
Add rice to skillet; cook over medium-high, stirring often, until most of the rice turns white, 1 to 2 minutes. Stir in beans, stock, corn, and 3/4 cup of the salsa; bring to a simmer over medium. Stir in 4 ounces of the cheese and remaining 3/4 teaspoon salt. Transfer mixture to baking dish; stir to combine. Cover with aluminum foil, and bake in preheated oven until rice is tender and chicken is done, about 45 minutes.
Remove from oven; uncover and sprinkle with remaining 2 ounces cheese. Increase oven temperature to high broil. Return baking dish to oven; broil until cheese is melted and lightly browned, about 2 minutes. Top with remaining 1/4 cup salsa.