Preheat oven to 400ᵒ and line a rimmed baking sheet with foil. Spray foil with cooking spray.
In a large bowl or ziplock bag mix olive oil, garlic salt, black pepper, cayenne pepper, paprika, and onion powder together. Coat drumsticks in mixture.
Place drumsticks on foil lined baking sheet and bake chicken for 20 minutes.
Remove from oven. Using a silicone brush, coat chicken with BBQ sauce and bake at 400ᵒ another 20 to 25 minutes (or until the chicken is done 165ᵒ) turning the heat up to 450ᵒ the last 5 minutes to caramelize. Cooking times vary based on size of drumsticks.