Begin by bringing a large pot of salted water to a boil. Add the fettuccine pasta and cook according to the package instructions until al dente. Once cooked, reserve 1/2 cup of the pasta water, then drain the fettuccine and set it aside.
While the pasta is cooking, generously season both sides of the chicken breasts with sea salt and freshly cracked black pepper.
In a large skillet, heat the olive oil over medium heat. Carefully add the seasoned chicken breasts to the skillet, cooking for 6-7 minutes on each side until they are golden brown and no longer pink in the center. Once fully cooked, remove the chicken from the skillet and set aside to rest for a few minutes before slicing it into thin strips.
In the same skillet, reduce the heat to low. Add the minced garlic and red pepper flakes (if using) to the pan. Sauté for about 1 minute, stirring frequently to prevent the garlic from burning.
Gradually pour in the heavy cream while stirring, increasing the heat slightly to bring the mixture to a gentle simmer. Once simmering, add in the grated Parmesan cheese, stirring continuously until the cheese melts completely and the sauce becomes creamy. If the sauce is too thick for your liking, slowly add some of the reserved pasta water until you reach your desired creaminess.
Add the cooked fettuccine to the skillet, tossing it gently to ensure it is thoroughly coated with the creamy sauce. Next, incorporate the sliced chicken, mixing everything until well combined and heated through.
Taste the dish and adjust the seasoning as needed, adding more salt and pepper to suit your palate.
Immediately plate the fettuccine and chicken, garnishing each serving with a sprinkle of freshly chopped parsley for a vibrant touch and added flavor.