Begin by bringing a large pot of salted water to a boil over high heat. Add fettuccine and cook according to package instructions, typically 8-12 minutes, until al dente. Before draining, reserve about a cup of the pasta cooking water.

In a large skillet, heat 2 tablespoons of olive oil over medium-high heat. Add diced or sliced chicken that has been seasoned with Cajun seasoning and cook for 6-8 minutes until golden brown and fully cooked.

Reduce heat to medium-low, return the skillet to the stovetop, and pour in 1 cup of heavy cream. Gradually whisk in ½ cup of finely grated Parmesan cheese until smooth and creamy. Allow the sauce to simmer for 3-5 minutes.

Add reserved fettuccine to the skillet with the creamy Cajun sauce and chicken, tossing to coat all the pasta evenly. If the sauce is too thick, add some reserved pasta water until desired creaminess.

Serve hot, garnished with freshly chopped parsley or sliced green onions.