Cut chicken breasts into bite-sized pieces, roughly 1.5 inches each.

Pat chicken dry with paper towels and season generously with salt and pepper on both sides.

Place a large skillet over medium-high heat and add olive oil. Allow it to shimmer for about 30 seconds.

Add the chicken to the hot skillet and let it sit undisturbed for the first 3 minutes to create a golden crust.

Stir and cook for another 2-3 minutes until chicken is golden on all sides but not cooked through.

Push chicken to sides of the skillet and add diced onion and minced garlic to the center. Cook for about 60 seconds until fragrant.

Pour bourbon into the skillet, scraping the bottom with a wooden spoon. Let it reduce slightly for 2-3 minutes.

Add soy sauce, brown sugar, red pepper flakes, and butter, stirring until sugar dissolves.

Reduce heat to medium and let the chicken simmer in the sauce for 4-5 minutes until it reaches an internal temperature of 165°F.

Mix cornstarch with 1 teaspoon of water and stir it in during the last minute of cooking if a thicker glaze is desired.

Taste the sauce and adjust seasoning with more salt, bourbon, or brown sugar as needed.