Steps
1. Preheat the oven to 375°F (190°C).
2. In a small bowl, mix the dark chocolate, rosemary, salt, pepper, garlic powder, and onion powder until well combined.
3. Carefully slice a pocket into the chicken breast without cutting all the way through.
4. Stuff the chocolate mixture into the pocket of the chicken breast.
5. Heat the olive oil in an oven-safe skillet over medium heat. Sear the chicken breast on both sides until golden brown, about 3-4 minutes per side.
6. Drizzle balsamic vinegar over the chicken and transfer the skillet to the preheated oven.
7. Bake for 20-25 minutes or until the chicken is fully cooked and reaches an internal temperature of 165°F (75°C).
8. Let rest for 5 minutes before slicing to serve.