Place the chicken thighs in the slow cooker.
In a bowl, whisk together the brown sugar, soy sauce, bourbon, apple cider vinegar, ground ginger, honey, red pepper flakes, and minced garlic.
Pour the sauce mixture over the chicken. Cover and cook on low for 6 hours or high for 4 hours, until the chicken is tender.
Remove the chicken and chop or shred it.
In a small bowl, mix the cornstarch and water until smooth, then stir it into the sauce in the slow cooker.
Return the chicken to the slow cooker, stir to combine, and let it cook for another 10-15 minutes to thicken.
Garnish with chopped green onions and serve over rice or your preferred side.