Cook the fettuccine according to package instructions; drain and set aside.
Season the chicken with salt and pepper.
In a skillet, melt 2 tablespoons of butter over medium heat.
Add the chicken and cook for about 6-7 minutes on each side until cooked through.
Remove the chicken from the skillet and let it rest before slicing it into strips.
In the same skillet, add the remaining butter and minced garlic; sauté for 1 minute.
Pour in the heavy cream and bring to a simmer, stirring occasionally.
Add the Parmesan cheese and mix until the sauce is smooth.
Toss the cooked fettuccine into the sauce, coating it evenly.
Add the sliced chicken on top and garnish with chopped parsley before serving.