Cook the long-grain rice according to package directions if starting from uncooked rice, or measure out 4 cups cooked day-old rice.
Stir together salt, pepper, garlic powder, onion powder, oregano, thyme, paprika, chilli powder, and 1 1/2 tablespoons Cajun seasoning, then coat the chicken.
Heat olive oil and 25 g butter in a large skillet over medium heat, then sear the chicken until golden and cooked to 165°F.
Move the chicken to a cutting board, rest for 5 minutes, then slice it into strips.
Cook the red onion and garlic in the same skillet until fragrant, then stir in the rice, 1/2 tablespoon Cajun seasoning, and parsley.
Melt 15 g butter in a small pan, add 1/2 tablespoon Cajun seasoning, milk, cream cheese, and Parmesan, then whisk until smooth.
Serve the garlic rice with sliced Cajun chicken, creamy sauce, and extra parsley on top.