Prep the chicken. Pat the chicken breasts dry and season both sides with salt, pepper, and a pinch of Italian seasoning. Pound to an even 1/2-inch thickness so they cook evenly.

Boil the pasta. Bring a large pot of salted water to a rolling boil. Cook fettuccine until just shy of al dente, about 1 minute less than package instructions. Reserve 1 cup of pasta water before draining.

Pan-sear the chicken. In a large skillet, heat 1 tablespoon olive oil and 1 tablespoon butter over medium-high heat. Add chicken and cook 4–5 minutes per side, until golden and cooked through (internal temp 165°F). Transfer to a plate, tent with foil, and rest 5 minutes. Slice into strips.

Start the Alfredo base. In the same skillet, lower heat to medium. Add 4 tablespoons butter. When melted, add garlic and cook 30–45 seconds until fragrant, not browned.

Add cream and optional cream cheese. Pour in heavy cream and whisk in the cream cheese until smooth. Simmer gently for 2–3 minutes. Do not boil—high heat can cause separation.

Incorporate Parmesan. Reduce heat to medium-low. Add the Parmesan in small handfuls, whisking constantly until melted and silky. Season with salt and pepper. If the sauce seems too thick, loosen with a splash of pasta water.

Combine pasta and sauce. Add drained fettuccine directly to the skillet. Toss until every strand is coated and glossy, 1–2 minutes. Add small amounts of pasta water as needed for a smooth, flowing sauce that clings to the noodles.

Add chicken. Fold in the sliced chicken. Warm through for 1 minute. If using, finish with a squeeze of lemon to brighten the richness.

Garnish and serve. Top with chopped parsley and a little extra Parmesan. Serve immediately while the sauce is at its silkiest.