Bring a large pot of salted water to a boil. Cook the fettuccine according to package instructions until al dente, then drain and set aside (reserve 1/2 cup of pasta water).

While the water heats, pound chicken breasts to an even thickness and coat them generously on both sides with the Cajun seasoning.

Heat the olive oil in a large skillet over medium-high heat. Add the chicken and cook for 5-7 minutes per side until blackened on the outside and fully cooked through (internal temperature of 165°F). Remove chicken to a plate to rest.

In the same skillet, reduce heat to medium and melt the butter. Add the minced garlic and sauté for 1 minute until fragrant, being careful not to burn it.

Pour in the heavy cream and whisk to combine, scraping up any browned bits left from the chicken for extra flavor. Let the mixture simmer gently for 3-5 minutes until it slightly thickens.

Remove the skillet from heat and gradually whisk in the Parmesan cheese until smooth and melted. Taste and season with salt and pepper as needed.

Toss the cooked fettuccine into the sauce until fully coated. If the sauce is too thick, add a splash of the reserved pasta water to loosen it.

Slice the resting chicken into strips.

Serve the creamy pasta in bowls topped with the sliced blackened chicken and garnished with fresh parsley.