Make sure to carefully follow each step of the instructions for the best results :
Season the chicken.
Mix together all the Cajun seasoning ingredients in a small bowl. Pat the chicken breasts dry, then coat them generously on both sides with the seasoning blend. Thin or pounded chicken pieces will cook more evenly, so if your breasts are thick, slice them in half lengthwise before seasoning.Sear the chicken.
Heat the olive oil and butter in a large skillet over medium-high heat. Once hot, add the chicken and sear for 4 to 5 minutes per side until a dark, golden crust forms and the chicken is cooked through. Transfer to a plate and set aside — the chicken will finish warming through in the sauce later.Build the sauce base.
Reduce the heat to medium and add the minced garlic to the same pan. Stir for about 30 to 60 seconds until fragrant. Pour in the chicken broth and scrape up any browned bits stuck to the bottom of the pan — that’s where a lot of the flavor lives. Let it reduce slightly for about a minute.Make the cream sauce.
Pour in the heavy cream and stir to combine. Add the sun-dried tomatoes and the extra Cajun seasoning, then let the sauce simmer gently for 2 to 3 minutes until it starts to thicken. Stir in the Parmesan a little at a time over low heat until it melts into the sauce smoothly.Finish with spinach and chicken.
Add the spinach and stir until wilted, which only takes about a minute. Return the seared chicken to the skillet and spoon the sauce over the top. Simmer everything together for 3 to 4 minutes so the flavors come together and the chicken heats through. Finish with fresh parsley and serve warm.