Season chicken with chicken alfredo seasoning, salt, and pepper.
Heat olive oil in a skillet and cook chicken for 6–7 minutes per side.
Remove chicken from skillet, let rest, and then slice.
Boil salted water, cook fettuccine until al dente, then drain.
Melt butter in skillet, add garlic, and sauté until fragrant.
Add heavy cream to skillet, stirring continuously.
Gradually add Parmesan cheese, stirring until sauce is smooth.
Toss fettuccine in alfredo sauce, adding pasta water if needed.
Top pasta with sliced chicken, parsley, and additional Parmesan.