Preheat your grill to 450°F (230°C).
Tenderize: Place chicken breasts in a heavy-duty baggie. Flatten to ½-¾ inch thickness using a meat mallet or rolling pin.
Season: Rub each chicken breast with olive oil. Then, generously rub with sea salt, black pepper, brown sugar, and smoked paprika. Let chicken sit at room temperature for a few minutes.
Grill: Place seasoned chicken breasts on the hot grill. Cook for 6 minutes per side, until they easily release from the grates.
Baste: After the first flip, brush each breast with BBQ sauce.
Finish cooking for an additional 2 minutes per side, or until the internal temperature reaches 165°F (74°C).