Mix the garlic powder, Italian seasoning, ½ tsp salt, and ¼ tsp black pepper, then rub over the chicken breasts. Heat the 2 tbsp olive oil in a large skillet over medium-high heat and sear the chicken for 5 to 6 minutes per side until it reaches 165°F (74°C) internally. Transfer to a cutting board to rest.

Bring a large pot of salted water to a boil over high heat, add the 12 oz fettuccine, and cook 10 to 11 minutes until al dente. Reserve ½ cup pasta water before draining.

In the same skillet over medium heat, melt the 4 tbsp butter, add the 4 cloves minced garlic, and cook for 1 minute. Pour in the 2 cups heavy cream and simmer gently for 3 to 4 minutes. Stir in the 1½ cups Parmesan in two additions, then add the ¼ tsp nutmeg and remaining ½ tsp salt and ¼ tsp pepper. Loosen with reserved pasta water if needed.

Add the drained fettuccine to the skillet and toss with tongs over low heat for 1 to 2 minutes until every strand is coated.

Slice the chicken into ½-inch strips, lay over the plated fettuccine, and finish with the 2 tbsp chopped parsley and an extra pinch of Parmesan.