Preheat oven to 450 degrees. Pound chicken breasts lightly so they are of even thickness.
Pour about 1/2-3/4 of a cup of barbecue sauce in a 13" x 9" baking dish.
In a small bowl, whisk together salt, pepper, garlic powder, onion powder and chili powder. Sprinkle the seasoning mixture over both sides of the chicken and rub it in with your hands. Place chicken breasts side by side in the prepared baking dish, making sure there is no overlap.
Brush with the barbecue sauce, enough to cover the chicken.
Bake in a preheated oven for 15 minutes, until juices are clear or a meat thermometer reads 160-170 degrees. Baste with more sauce after about 10-12 minutes.
Turn the broiler to high and move chicken to the top rack of the oven. Broil for about 5 minutes, or until sauce is caramelized and nice and sticky - careful to watch closely to avoid burning.
Cover with foil and allow to rest for 5-10 minutes while the juices settle before slicing.