Bring a large pot of salted water to a boil. Cook fettuccine until al dente according to package directions. Reserve 1 cup pasta water, then drain pasta.

Halve each chicken breast lengthwise so pieces are thin and cook evenly. Pat dry.

Season both sides of chicken with salt, pepper, garlic powder, and Italian seasoning.

Heat 2 tbsp butter in a large skillet over medium-high heat. Add chicken and sear until golden, about 3–4 minutes per side, or until internal temperature reaches 165°F (74°C). Remove chicken to a cutting board and let rest 5 minutes, then slice.

In the same skillet, reduce heat to medium-low and add 1/2 cup (1 stick) butter. Melt, then add minced garlic and gently cook 30–45 seconds until fragrant.

Pour in heavy cream and bring to a gentle simmer. Stir in salt and pepper. Let the cream warm for 2–3 minutes — do not boil.

Gradually whisk in shredded Parmesan until smooth. If the sauce is too thick, stir in a tablespoon or two of reserved pasta water until you reach the desired consistency.

Add drained fettuccine to the skillet and toss to coat evenly. Slice chicken and arrange on top or toss through the pasta.

Taste and adjust salt/pepper. Garnish with a sprinkle of dried parsley and serve immediately.

Serve right away for the creamiest texture.