Pat the chicken dry and halve it lengthwise (if not already). Season both sides with salt, 1 tsp smoked paprika, 1 tsp garlic powder, and 1/2 tsp black pepper. Add 1 tbsp oil and rub to coat. Marinate for 30 minutes.

Bring a large pot of generously salted water to a boil. Add 9 oz fettuccine and cook until al dente according to package directions. Reserve 1 cup of the pasta cooking water, then drain the pasta and set aside.

Heat 2 tbsp oil in a large skillet over medium-high heat. Add the marinated chicken and cook 4–5 minutes per side (depending on thickness) until cooked through and golden. Transfer the chicken to a cutting board and let rest for a few minutes, then slice.

In the same skillet over medium heat, add 5 tbsp butter. Once melted, sprinkle in 1 1/2 tbsp all-purpose flour and whisk constantly for 30–40 seconds to cook out the raw flour taste (do not allow the roux to brown).

Slowly whisk in 1 1/2 cups room-temperature heavy cream until smooth. Season with salt to taste, 1/2 tsp black pepper, 1 tsp garlic powder, 1 tsp Italian seasoning, and 1 tsp dried parsley.

Simmer gently for 3–4 minutes, stirring frequently, until the sauce is slightly thickened.

Reduce heat to low and stir in 3/4 cup freshly grated Parmesan cheese until melted and smooth. Stir in 1 tbsp lemon zest and 2 tsp lemon juice. Taste and adjust salt or lemon as needed.

Add the cooked fettuccine to the sauce. Toss gently and add reserved pasta water 1/4 cup at a time as needed, until the sauce becomes silky and coats the pasta evenly.

Add the sliced chicken to the pasta and toss again. Simmer on low for 1–2 minutes to let everything come together.

Serve immediately, garnished with extra Parmesan, chopped parsley (or dried parsley), and a pinch of black pepper. Optional: drizzle a tiny bit of olive oil or a small pat of butter on top for extra gloss.