Season the chicken breasts generously with Cajun seasoning on both sides.
Heat olive oil in a skillet over medium-high heat.
Cook the chicken until blackened and fully cooked, about 5–6 minutes per side.
Remove chicken from skillet and let it rest before slicing.
Boil fettuccine pasta in salted water according to package instructions.
In the same skillet, melt butter over medium heat.
Add minced garlic and sauté until fragrant.
Pour in heavy cream and bring to a gentle simmer.
Stir in Parmesan cheese, salt, and black pepper until smooth.
Add drained pasta to the sauce and toss to coat evenly.
Slice the chicken and place on top of the pasta.
Garnish with fresh parsley and serve hot.