01 - Whisk together buttermilk, mayonnaise, ranch seasoning, minced garlic, olive oil, dried parsley, black pepper, paprika, and salt in a large bowl until well combined.
02 - Add chicken cubes to the marinade, toss to coat evenly. Cover and refrigerate for at least 30 minutes, up to 2 hours for deeper flavor penetration.
03 - Preheat grill or grill pan to medium-high heat. If using wooden skewers, soak in water for 30 minutes to prevent burning.
04 - Thread marinated chicken pieces onto skewers, leaving small space between each piece for even cooking.
05 - Lightly oil grill grates. Place skewers on grill and cook for 5 to 7 minutes per side, turning once, until chicken reaches internal temperature of 165°F and develops grill marks.
06 - During the last 2 minutes of grilling, sprinkle Parmesan cheese generously over skewers. Close grill lid to melt cheese.
07 - Remove skewers from grill. Garnish with chopped fresh parsley if desired. Serve immediately while hot.