Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a large mixing bowl, combine the ground chicken, breadcrumbs, grated Parmesan cheese, minced green onions, minced garlic, the egg, salt, black pepper, and red pepper flakes (if using). Mix until fully combined.
Roll portions of the chicken mixture into meatballs, about 1 inch in diameter, and place them on the prepared baking sheet.
Bake the meatballs for 20-25 minutes until golden brown and cooked through (internal temperature of 165°F/74°C).
In a small saucepan over medium heat, combine honey, soy sauce, apple cider vinegar, and sesame oil. Heat until simmering and slightly thickened, about 5 minutes.
Transfer the baked meatballs to a large mixing bowl and pour the warm honey garlic sauce over them, gently tossing to coat.
Let the meatballs rest for a few minutes to soak up the flavors.
Serve hot, garnished with sesame seeds and sliced green onions.
Notes
For an eye-catching presentation, arrange the meatballs on a serving platter and drizzle with remaining sauce.