01 - In a small saucepan, combine the Coca-Cola, ketchup, soy sauce, brown sugar, apple cider vinegar, garlic powder, smoked paprika, black pepper, and salt. Bring to a simmer over medium heat, stirring occasionally, until the mixture reduces by about half and thickens to a syrupy consistency, 10 to 12 minutes. Set aside to cool slightly.
02 - Pat the chicken breasts dry with paper towels and brush each with olive oil. Season lightly with additional salt and pepper.
03 - Reserve 1/3 cup of the prepared glaze for basting during grilling. Place the chicken breasts and the remaining glaze in a large resealable plastic bag or shallow dish, turning to coat evenly. Refrigerate for at least 30 minutes, or up to 2 hours for more pronounced flavor.
04 - Preheat an outdoor grill or grill pan to medium-high heat, approximately 400°F. Oil the grates generously to prevent sticking.
05 - Remove the chicken from the marinade and discard the used marinade. Place the breasts on the hot grill and cook for 5 to 7 minutes per side, basting frequently with the reserved glaze, until the internal temperature reaches 165°F and the exterior is deeply caramelized.
06 - Transfer the chicken to a cutting board and let rest for 5 minutes. Slice against the grain and drizzle with any remaining glaze before serving.