Bring a large pot of salted water to a rolling boil. Add the fettuccine and cook until al dente according to package instructions, approximately 10 minutes. Reserve 1/2 cup of the pasta water, drain the noodles, and set aside.

Season the chicken breasts evenly with kosher salt, Italian seasoning, and black pepper. Heat olive oil in a large nonstick skillet over medium-high heat until shimmering. Place the chicken into the pan, ensuring an even layer, and cook undisturbed for 5 to 7 minutes until the underside is golden. Flip the chicken, add the butter to the pan, and gently swirl to coat. Continue cooking for 5 to 7 minutes, or until the internal temperature reaches 165°F.

Transfer the chicken to a cutting board, allow it to rest for 3 minutes, then slice into 1/2-inch-thick pieces. Cover loosely with foil while you prepare the sauce.

Using the same skillet, reduce the heat to medium-low. Melt the butter and whisk it together with the heavy cream until smooth. Add the minced garlic, garlic powder, Italian seasoning, salt, and pepper, whisking continuously to combine. Simmer gently (do not boil) for 3 to 4 minutes until slightly thickened.

Gradually stir in the grated Parmesan cheese until fully melted and the sauce is smooth. If the consistency is too thick, incorporate a few tablespoons of the reserved pasta water to thin it to your liking.

Remove the sauce from the heat and toss immediately with the cooked fettuccine until evenly coated. Divide the pasta into individual serving bowls, topping each with slices of chicken. Garnish with freshly chopped parsley, additional Parmesan, and a sprinkle of black pepper if desired.