Preheat oven to 375°F. Lightly grease a 9×13-inch baking pan with cooking spray.

In a medium skillet over medium heat, melt 1 tablespoon butter. Add cubed chicken, season with ½ teaspoon salt and lemon pepper, and sauté just until edges turn opaque (about 2–3 minutes). Transfer chicken to a plate.

In a bowl, whisk together chicken broth, lemon juice, remaining melted butter, lemon zest, garlic, onion powder, basil, pepper, thyme, and ½ teaspoon salt. Stir in rice until evenly coated.

Pour rice mixture into the prepared pan. Nestle the seared chicken into the rice, then top with lemon slices and any pan juices.

Cover tightly with foil and bake 30 minutes. Uncover and bake 5–7 more minutes, until rice is tender and chicken is cooked through. Let rest 5 minutes before serving.