Pour the bourbon into a small or medium saucepan and set it over medium heat. Let it gently simmer for about 3–4 minutes, stirring occasionally, until the sharp alcohol smell softens. Do not walk away, as it can boil over if the heat is too high.
1 cup bourbon
Stir in the brown sugar, maple syrup, and honey (if using). Whisk until the sugar dissolves and the mixture looks smooth and glossy. It will be fairly thin at this point, like simple syrup.
1 cup brown sugar, 2 tablespoons pure maple syrup, 2 tablespoons honey
Add the apple cider vinegar, Dijon mustard, and Worcestershire sauce. Whisk well to fully combine and break up any mustard bits. Taste carefully (it will be hot) to check the balance of sweet and tangy.
2 tablespoons apple cider vinegar, 1 tablespoon Dijon mustard, 1 teaspoon Worcestershire sauce
Sprinkle in the salt, black pepper, crushed red pepper flakes, smoked paprika, and garlic. Stir and bring the mixture back to a gentle simmer. Cook for 1–2 minutes until the garlic softens and becomes fragrant.
1 teaspoon kosher salt, 1/2 teaspoon black pepper, 1/4-1/2 teaspoon crushed red pepper flakes, 1/2 teaspoon smoked paprika, 1 clove garlic
Reduce the heat to medium-low and let the glaze simmer uncovered for about 8–12 minutes, stirring occasionally, until it reduces and thickens enough to coat the back of a spoon. Remember it will continue to thicken as it cools, so avoid over-reducing.
If you prefer a very thick, clingy glaze, stir together the cornstarch and cold water in a small bowl to make a slurry. Whisk the slurry into the simmering glaze and cook for 1–2 minutes, stirring, until it visibly thickens. If it becomes too thick, add a tablespoon or two of water or extra bourbon to loosen.
1-2 teaspoons cornstarch, 1 tablespoon cold water
Turn off the heat and stir in the butter until fully melted and incorporated. This adds sheen and a silky finish. Taste and adjust salt, pepper, or vinegar to your liking.
1 tablespoon unsalted butter
Let the bourbon glaze sit for 5–10 minutes before brushing on meat. It should be warm and pourable, not scorching hot. If it thickens too much as it sits, warm gently on low heat and stir in a teaspoon or two of water.