Bring a large pot of water to a rolling boil. Add a generous tablespoon of salt. Cook the fettuccine according to package directions until al dente. Reserve about 1 cup of the pasta cooking water before draining. Drain the rest and set aside.

Season the thinly sliced chicken breasts generously with salt, pepper, and a little garlic powder and onion powder. Heat the olive oil in a large skillet or Dutch oven over medium-high heat. Add the chicken and cook for 5-7 minutes per side until golden brown and cooked through. Remove from skillet, let rest, then slice into strips.

Reduce heat to medium-low. Add minced garlic to the skillet (and a touch more oil if dry). Sauté for 30 seconds until fragrant. Sprinkle flour over the mixture and whisk for 1 minute. Slowly whisk in the milk and chicken broth until smooth. Simmer for 3-5 minutes until thickened.

Remove from heat. Stir in Parmesan cheese until melted and smooth. Season with salt, pepper, and nutmeg.

Toss drained pasta and sliced chicken into the skillet with the sauce. Stir to coat evenly. If too thick, add reserved pasta water a splash at a time for desired consistency. Garnish with parsley and serve hot.