Bring a large pot of salted water to a rolling boil. Add fettuccine and cook according to package directions until al dente.

Before draining, reserve 1 cup of the pasta cooking water. Drain the pasta and set aside.

While the pasta cooks, pat the chicken dry and season both sides with salt and pepper.

Heat olive oil in a large skillet over medium-high heat. Add the chicken and cook 5–7 minutes per side until golden and cooked through (internal temp 165°F / 74°C).

Transfer chicken to a plate and let it rest for 5 minutes, then slice thinly against the grain.

Reduce the skillet heat to medium. Add butter and let it melt. Add minced garlic and cook for about 30 seconds until fragrant, without browning.

Slowly whisk in heavy cream. Bring the mixture to a gentle simmer and cook for 3–4 minutes, stirring, until the cream thickens slightly.

Reduce heat to low. Gradually add freshly grated Parmesan, whisking until smooth and fully melted. Season with salt, freshly ground black pepper, and a pinch of nutmeg.

Add the drained fettuccine to the skillet and toss to coat the pasta in the sauce. If the sauce seems too thick, add a splash of the reserved pasta water and toss until you reach the desired consistency.

Return the sliced chicken to the pan and toss briefly so everything is heated through.

Plate immediately and garnish with chopped parsley and extra Parmesan.