Cook the fettuccine according to package instructions.
In a large skillet, melt the butter over medium heat.
Add the chicken breasts to the skillet, seasoning with salt and pepper, and cook until golden and cooked through.
Remove the chicken from the skillet and set aside, leaving the drippings in the pan.
Add the minced garlic to the skillet and sauté until fragrant.
Pour in the heavy cream, stirring to combine with the garlic and drippings.
Add the grated Parmesan cheese to the cream and stir until melted and smooth.
Slice the cooked chicken and add it to the sauce, then mix in the drained fettuccine.
If the sauce is too thick, adjust with reserved pasta water; if too thin, simmer a bit longer.
Serve hot, garnished with fresh parsley.