Preheat oven to 325 . Remove insides of chicken and discard. Cut onion in half and stuff inside chicken.
Mix all dry seasonings in a bowl. Loosen skin and put seasoning under skin in breast area , as best as you can. Sprinkle the rest over entire chicken , covering really good. Inject chicken with Jalapeno Butter , get as much as you can in chicken. THROW AWAY ANY LEFTOVER JALAPENO BUTTER AND THE INJECTOR .
Spray dish with cooking spray . Put chicken (breast side up ) in covered dish . Cook for about 1 hour , remove lid and add BBQ sauce . Put lid back on and return to oven and cook 1 hour more....remove lid and cook 15 minutes .