Bring a large pot of salted water to a boil. Add the fettuccine and cook according to package instructions until al dente. Drain and set aside.

In a skillet, heat olive oil over medium heat. If using chicken or shrimp, add them now and cook until fully cooked through. Remove and set aside.

In the same skillet, add heavy cream and bring to a simmer. Stir in Parmesan cheese, Cajun seasoning, garlic powder, onion powder, salt, and pepper. Cook until the sauce thickens, about 5 minutes.

If you cooked chicken or shrimp, return them to the skillet and combine with the sauce.

Add the cooked fettuccine to the skillet and toss to coat in the sauce. Serve immediately, garnished with additional Parmesan if desired.