Prep the Chicken: Begin by cutting the chicken into bite sized pieces. This helps the sauce coat everything evenly later. Lightly grease the crockpot with olive oil, then place the chicken inside in an even layer.
Mix the Sauce: In a bowl, whisk together soy sauce, brown sugar, ketchup, bourbon, garlic, ginger, black pepper, and red pepper flakes if using. Stir until the sugar starts dissolving and the mixture looks smooth and glossy.
Combine and Cook: Pour the sauce over the chicken in the crockpot. Gently stir so every piece gets coated. Cover with the lid and cook on low heat for 4 to 5 hours. During this time, the chicken absorbs flavor while the sauce deepens and darkens.
Thicken the Sauce: Once the chicken finishes cooking, mix cornstarch and water in a small bowl. Pour it into the crockpot and stir well. Turn the heat to high and cook uncovered for about 20 minutes until the sauce thickens into a sticky glaze.
Final Stir and Rest: Give everything a final stir and let it rest for a few minutes. This short pause helps the sauce settle and cling better to the chicken before serving.
