Preheat the barbecue grill to medium-high.
Season the inside and outside of the chicken breasts with the Creole seasoning. Add 1 piece of fennel with fronds to the inside of each breast. Close the breasts and drizzle the outside of each with olive oil.
Once the grill is hot, add the chicken, oiled side down, close the grill, and cook for 4 minutes.
Brush the chicken with additional oil and turn to the other side. Close the grill, and cook for another 4 minutes.
Flip the breasts once more and baste with BBQ sauce, close the grill, and cook for another 4 minutes.
Right before removing from grill, flip the chicken and baste with BBQ sauce a final time. Remove the chicken to a platter and allow it to rest at least 3 minutes before serving. Combine all ingredients thoroughly.