01 - Whisk together buttermilk, mayonnaise, ranch seasoning, minced garlic, olive oil, dried parsley, black pepper, paprika, and salt in a large bowl until smooth and well combined.
02 - Add chicken cubes to the marinade, tossing thoroughly to coat all pieces. Cover bowl and refrigerate for at least 30 minutes, up to 2 hours for maximum flavor penetration.
03 - Heat grill or grill pan to medium-high temperature. Soak wooden skewers in water for 30 minutes if using to prevent burning.
04 - Remove chicken from marinade and thread onto skewers, leaving small gaps between pieces for even cooking. Discard remaining marinade.
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 distinct grill marks.
06 - During the final 2 minutes of cooking, generously sprinkle Parmesan cheese over each skewer. Close grill lid to allow cheese to melt and slightly crust.
07 - Transfer skewers to serving platter. Garnish with fresh chopped parsley if desired. Serve immediately while hot.