01 - Whisk together buttermilk, mayonnaise, ranch seasoning, minced garlic, olive oil, dried parsley, black pepper, paprika, and salt in a large bowl until smooth.
02 - Add chicken cubes to the marinade, toss to coat evenly. Cover and refrigerate for 30 minutes to 2 hours.
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 gaps between pieces for even cooking.
05 - Lightly oil grill grates. Cook skewers for 5–7 minutes per side, turning once, until chicken reaches 165°F internally and develops grill marks.
06 - Sprinkle Parmesan cheese generously over skewers during the last 2 minutes. Close grill lid to melt cheese.
07 - Remove skewers from grill. Garnish with fresh parsley if desired. Serve immediately.