Pat the chicken dry and season it with salt, pepper, garlic powder, and smoked paprika powder. Add oil and mix well to combine. Let it marinate for 30 minutes.
Bring a large pot of generously salted water to a boil. Cook fettuccine until al dente. Reserve 1 cup pasta water, then drain.
In a pan add oil add the marinated chicken and cook for 4–5 minutes per side on medium-high heat, depending on thickness. Remove the chicken in the same pan add butter once the butter is melted. Add chili oil. Cook for 30 sec.
Add all purpose flour. Whisk constantly for 30-40 sec to cook out the raw taste (do not brown). Add in heavy whipping cream. Mix and add salt, garlic powder, black pepper, dried parsley, smoked paprika powder.
Simmer gently for 3–4 minutes, stirring, until slightly thickened. Reduce heat to low, then stir in Parmesan cheese until melted and smooth. Add lemon juice. Taste and adjust salt or lemon if needed.
Add cooked fettuccine to the sauce. Toss gently, adding reserved pasta water a little at a time until the sauce is silky and coats the pasta beautifully. Add sliced chicken and toss again. Simmer on low for 1–2 minutes to let everything come together.
Garnish with extra Parmesan, parsley, or a pinch of black pepper.
