01 - In a small bowl, thoroughly combine all ingredients for the Cajun Spice Blend.
02 - Pat the chicken breasts completely dry with paper towels. Lightly rub both sides of each breast with olive oil, then generously coat them with the prepared Cajun spice mixture.
03 - Heat a large cast-iron skillet over medium-high heat. Add the butter (or dairy-free alternative) and allow it to melt and slightly foam.
04 - Carefully place the seasoned chicken breasts into the hot skillet. Sear each side for 3–4 minutes, or until a well-blackened crust forms. Reduce the heat to medium-low, cover the skillet, and continue cooking for an additional 8–10 minutes, or until the internal temperature of the chicken reaches 165°F (74°C). Remove the chicken from the skillet and let it rest for 5 minutes.
05 - While the chicken cooks, rinse the long-grain white rice under cold running water until the water runs clear. In a medium saucepan, bring the chicken broth (or water) and salt to a boil. Add the rinsed rice, give it a quick stir, then reduce the heat to low. Cover the saucepan tightly and simmer for 15 minutes, or until all the liquid has been absorbed. Remove from heat and let it stand, covered, for another 5 minutes before fluffing gently with a fork.
06 - Slice the rested blackened chicken breasts. Serve the chicken over a generous bed of the cooked rice. Garnish with chopped fresh parsley and lemon wedges, if desired.