01 - Bring a large pot of salted water to a boil. Cook the pasta according to package directions until al dente. Drain, reserving 1/2 cup pasta water, and set pasta aside.
02 - Pat chicken dry and season both sides with salt, black pepper, and garlic powder.
03 - Heat olive oil in a large skillet over medium-high heat. Add chicken and cook 5 to 6 minutes per side, until golden and cooked through. Remove from skillet and let rest 5 minutes before slicing thinly.
04 - In the same skillet, melt butter over medium heat. Add minced garlic and sauté for 1 minute until fragrant.
05 - Pour in heavy cream and whole milk, bringing to a gentle simmer while stirring constantly.
06 - Reduce heat to low. Stir in grated Parmesan and nutmeg if using. Continue stirring until cheese melts and sauce is smooth. Season with salt and black pepper to taste.
07 - Add cooked pasta to sauce, tossing well to coat. Add reserved pasta water as necessary to loosen the sauce.
08 - Arrange sliced chicken over the pasta. Garnish with chopped fresh parsley and extra Parmesan. Serve immediately.