Preheat the oven to 375 degrees Fahrenheit. Spray a 9×13-inch baking dish with non-stick cooking spray.
In the prepared baking dish, add 2 ½ cups chicken broth, 1 cup white rice, 3 tablespoons lemon juice, 3 tablespoons melted butter, 1 tablespoon lemon zest, 1 tablespoon minced garlic, 1 teaspoon onion powder, 1 teaspoon salt, 1 teaspoon dried basil, ½ teaspoon pepper, and ½ teaspoon thyme. Stir gently to combine and spread the rice mixture in an even layer.
Season the 1 pound cubed boneless skinless chicken breast with 1 teaspoon salt and 2 teaspoons lemon pepper, coating all sides.
Arrange the seasoned chicken pieces on top of the rice mixture in a single layer.
Cover the baking dish tightly with aluminum foil.
Bake covered for 30 minutes.
Remove the foil, arrange the thin slices from 1 lemon over the top, and return the dish to the oven. Bake uncovered for an additional 5 minutes, until the rice is tender and the chicken is cooked through.
Remove from the oven and let the casserole rest for 5 minutes before serving.