Combine all the spices, brown sugar, and oil in a small bowl.
Preheat a skillet or grill to high heat.
Rub the spice mixture over the chicken breasts.
Place the spice-rubbed chicken breasts on the hot grill or skillet.
Cook for about 4 minutes on each side, until the exterior is very deep, dark brown and the inside is no longer pink.
Remove from heat and let rest for 5-10 minutes to let the juices soak in before cutting.
