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. Soak wooden skewers in water for 30 minutes if using.
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 5–7 minutes per side, turning once, until chicken reaches internal temperature of 165°F and develops grill marks.
06 - Sprinkle Parmesan cheese generously over skewers during the last 2 minutes of grilling. Close lid to melt cheese.
07 - Remove skewers from grill, garnish with fresh parsley if desired, and serve immediately.