Start by boiling a large pot of salted water. Cook the fettuccine until al dente, usually around 10 minutes. Reserve half a cup of pasta water before draining to adjust sauce consistency later.
Season the chicken breasts with Italian seasoning, salt, and pepper. Heat olive oil in a skillet until shimmering, then sear chicken for 5-7 minutes on each side, adding butter halfway through. Cook until internal temperature reaches 165°F for juicy, tender chicken.
Melt butter in a skillet over medium heat, then stir in heavy cream and garlic. Add garlic powder, Italian seasoning, salt, and pepper, simmering for a few minutes. Gradually whisk in Parmesan until smooth and creamy.
Toss the cooked pasta in the Alfredo sauce, adding reserved pasta water if needed to reach your desired consistency. Slice the chicken and place on top, allowing the sauce to coat each piece evenly.
Garnish with extra Parmesan or fresh parsley before serving. The creamy sauce clinging to the fettuccine makes every bite satisfying.