Season the chicken with salt, pepper, and garlic powder.
Place the chicken into the slow cooker.
In a bowl, whisk together the garlic, honey, soy sauce, ketchup, brown sugar, rice vinegar, and grated ginger.
Pour the sauce over the chicken.
Cover and cook on LOW for 5 to 6 hours or HIGH for 2½ to 3½ hours.
Remove the chicken and shred it with two forks or leave it in larger pieces.
Whisk together the cornstarch and cold water until smooth.
Stir the slurry into the sauce in the slow cooker.
Cook on HIGH for 10 to 15 minutes until the sauce thickens.
Return the chicken to the slow cooker and toss until fully coated.
Garnish with green onions and sesame seeds before serving.