01 - Bring a large pot of salted water to a boil. Cook fettuccine according to package directions until al dente. Reserve 1/2 cup pasta water, then drain and set aside.
02 - Pat chicken breasts dry with paper towels. Season both sides generously with salt and pepper.
03 - Heat olive oil in a large skillet over medium-high heat. Add chicken breasts and cook 5-6 minutes per side until golden brown and internal temperature reaches 165°F. Remove to a plate, let rest 5 minutes, then slice into thin strips.
04 - In the same skillet, reduce heat to medium. Add butter and minced garlic. Sauté 1 minute until fragrant but not browned.
05 - Pour in heavy cream and bring to a gentle simmer. Stir in Parmesan cheese until completely melted and smooth. Add nutmeg if desired. Season with salt and pepper to taste.
06 - Add cooked pasta to the skillet and toss to coat evenly in sauce. Add reserved pasta water a little at a time if sauce needs thinning.
07 - Gently fold sliced chicken into the pasta. Serve immediately topped with fresh parsley and additional Parmesan cheese.