Bring a large pot of salted water to a boil. Add the pasta and cook until al dente according to package directions. Drain and set aside.

Season the chicken all over with Italian seasoning, salt, and pepper.

Heat the olive oil in a large nonstick skillet over medium-high heat. Once the oil is glistening, add the chicken and cook, undisturbed, until browned, 4 to 6 minutes per side. Add the butter to the pan and cook, turning occasionally, until the internal temperature of the chicken reaches 165°F, about 16 minutes. Remove the pan from the heat.

Transfer the chicken to a cutting board and let rest for 3 minutes. Cut into ½-inch thick slices and tent with foil to keep warm.

Wipe out the skillet and return it to medium heat. Add the butter. When the butter is nearly melted, add the garlic, garlic powder, nutmeg, salt, and pepper. Cook, stirring, until fragrant, about 1 minute.

Increase the heat to medium-high and gradually stir in the heavy cream. Bring to a simmer, then add the Parmesan; cook, stirring, until fully incorporated, about 2 minutes. Reduce the heat to medium-low and cook, stirring, until thickened, about 5 minutes more. Add the pasta and toss to coat.

Divide the pasta between bowls and top with the sliced chicken. Sprinkle with parsley and season with pepper to taste.