Start by seasoning the chicken breasts with Cajun seasoning, ensuring they are evenly coated on both sides.
In a large skillet, heat the olive oil over medium-high heat. Once hot, add the seasoned chicken breasts and cook for about 6-7 minutes on each side, or until the chicken is cooked through and has a nice blackened crust. Remove from the skillet and let rest for a few minutes before slicing.
While the chicken is resting, cook the fettuccine pasta according to package instructions until al dente. Drain and set aside.
In the same skillet used for the chicken, melt the butter over medium heat. Add the minced garlic and sauté for about 1 minute until fragrant.
Pour in the heavy cream and bring to a gentle simmer. Stir in the grated Parmesan cheese until melted and smooth. Season with salt and pepper to taste.
Add the cooked fettuccine to the sauce, tossing to coat the pasta evenly.
Slice the blackened chicken and arrange it on top of the pasta. Garnish with chopped parsley before serving.