Begin by cooking the fettuccine pasta according to package instructions in a large pot salted boiling water. Drain and set aside, saving about ½ cup of the pasta water.
While the pasta cooks, season the chicken breasts with salt, pepper, and Italian seasoning on both sides.
In a large skillet, heat olive oil over medium heat. Add the chicken breasts and cook for about 6-7 minutes on each side until golden brown and cooked through. Remove from the pan and let it rest for a few minutes before slicing it into strips.
In the same skillet, add minced garlic and sauté for about 1 minute until fragrant.
Pour in the heavy cream and bring it to a simmer. Gradually add the grated Parmesan cheese, stirring until melted and the sauce thickens. If the sauce is too thick, add some reserved pasta water to reach desired consistency.
Add the cooked fettuccine to the skillet and toss it in the creamy sauce until well coated.
Incorporate the sliced chicken into the mix and stir gently to combine. If using, add the halved cherry tomatoes for a burst of flavor and freshness.
Adjust seasoning with salt and pepper if needed.
Serve immediately, garnished with chopped fresh parsley.