3 Tablespoons of bourbon is all you need, which is about the size of a mini shooter (50ml) you can find at the liquor store. It will add caramelized sweetness to the sauce which is exactly what we want. That said, if you would still like to omit the bourbon then you can substitute it with apple juice.
We use chicken thighs because we love the flavor it adds to the dish, however, you can substitute with chicken breasts if that's what you prefer.