Heat the olive oil in a large skillet over medium heat. Season both sides of the chicken breasts with Cajun seasoning, garlic powder, onion powder, smoked paprika, salt, and black pepper.

Place the seasoned chicken in the hot skillet and cook for 6 to 7 minutes per side until golden brown and cooked through to an internal temperature of 165 degrees F. Remove and let rest on a cutting board for 5 minutes.

In the same skillet, melt the butter over medium heat. Add the minced garlic and saute for 1 to 2 minutes until fragrant and lightly golden.

Pour in the heavy cream and chicken broth, stirring to combine. Bring to a gentle simmer and cook for 3 to 4 minutes until the sauce thickens slightly.

Stir in the grated Parmesan cheese until fully melted and the sauce is smooth. While the sauce simmers, cook the fettuccine according to package directions. Drain, reserving 1/2 cup of pasta water.

Slice the rested chicken into thin strips. Add the drained fettuccine to the skillet and toss to coat evenly. Add reserved pasta water a tablespoon at a time if the sauce is too thick.

Stir in the chopped parsley and lemon juice, then add the sliced chicken on top. Toss everything together until well combined and heated through. Serve immediately with extra parsley if desired.