Slice eggplants into one-inch pieces and set onto paper towels to remove as much moisture as possible.
While you dry your eggplants, combine the hoisin, honey, ketchup, apple cider vinegar, soy sauce, Worcestershire sauce, minced garlic, minced ginger, olive oil, parsley, and red pepper flakes in a small bowl. Reserve half for dipping later.
Preheat a grill pan over medium-high heat and coat with cooking spray.
Dip your dried eggplant into the remaining dip and place onto the grill for about 2 minutes per side, rotating 90 degrees to achieve criss-crossing grill lines.
Brush continuously with the sauce until a sticky coating forms. Serve with a side of sauce and enjoy!