1. Prepare the Chicken:

1. Place the well-trimmed chicken thighs into the slow cooker.

2. Make the Sauce:

1. In a medium mixing bowl, whisk together the brown sugar, soy sauce, bourbon whiskey, apple cider vinegar, ginger, honey, red pepper flakes, and minced garlic.
2. Pour the sauce over the chicken thighs in the slow cooker.

3. Slow Cook:

1. Cover and cook on high for 4 hours, or low for 6 hours, or until the chicken is cooked through.

4. Thicken the Sauce:

1. Remove the chicken thighs to a plate and roughly chop them.
2. In a small bowl, whisk together the cornstarch and water until the cornstarch is dissolved.
3. Pour the cornstarch mixture into the sauce in the slow cooker and whisk to combine.  
4. Add the chopped chicken back to the sauce and stir to coat.
5. Cover and cook for a few more minutes, or until the sauce thickens and bubbles.

5. Garnish and Serve:

1. Sprinkle with chopped green onions and serve over rice.