Preheat your grill to medium-high heat.
In a large bowl, whisk together the olive oil, Parmesan cheese, minced garlic, Italian seasoning, salt, and black pepper until well combined.
Add the chicken breasts to the bowl and coat them evenly with the marinade. Cover and let marinate for at least 30 minutes in the refrigerator (or up to 2 hours for more flavor).
Once marinated, remove the chicken from the refrigerator and let it sit at room temperature for about 10 minutes before grilling.
Place the chicken on the preheated grill and cook for 6-7 minutes on each side, or until the internal temperature reaches 165°F and the chicken is golden brown.
Remove the chicken from the grill and let it rest for 5 minutes before slicing.
Garnish with chopped parsley and serve warm.