Bring a large pot of well-salted water to a boil. Cook 6 ounces fettuccine until about 1 minute shy of al dente. Reserve 1/2 cup pasta water, then drain.

Pat 8 ounces chicken dry and season with 1/2 teaspoon salt, 1/2 teaspoon garlic powder, 1/4 teaspoon black pepper, and 1/4 teaspoon Italian seasoning.

Heat 1/2 tablespoon olive oil and 1 tablespoon butter in a large skillet over medium-high heat. Cook the chicken until deeply golden and 165°F in the thickest part, about 3 to 5 minutes per side depending on thickness. Rest 5 minutes, then slice.

Reduce the skillet to medium-low. Melt 2 tablespoons butter, add 2 minced garlic cloves, and cook about 30 seconds, just until fragrant.

Pour in 3/4 cup heavy cream and bring to a very gentle simmer for 2 minutes. Reduce the heat to low and gradually stir in 3/4 cup freshly grated Parmesan until smooth. Add 1/4 teaspoon black pepper.

Add the drained fettuccine and toss continuously. Add reserved pasta water 1 to 2 tablespoons at a time until the sauce is glossy and coats the noodles rather than sitting heavily on them. Taste before adding any extra salt.

Divide the fettuccine between two bowls and top with the sliced chicken. Finish with a little more Parmesan and black pepper if desired.