Season the chicken breasts with Cajun seasoning.
Heat a skillet over medium heat and add butter.
Cook the chicken for 6-7 minutes on each side until fully cooked.
Remove the chicken and let it rest before slicing.
In the same skillet, add minced garlic and sauté for 1 minute.
Pour in heavy cream and bring to a simmer.
Stir in Parmesan cheese until melted and smooth.
Cook fettuccine according to package instructions; drain.
Combine pasta with Alfredo sauce in the skillet.
Serve the pasta topped with sliced chicken and garnish with parsley.