Spoon rice mixture evenly onto centre of each of four large sheets of heavy-duty foil. Top each with 1 chicken breast; sprinkle with chili powder. Drizzle evenly with dressing; top with cheese and vegetables. Bring up foil sides. Double fold top and both ends to seal each packet, leaving room for heat circulation inside. Place foil packets in single layer in 15x10x3/4-inch baking pan.