Begin by pouring 1 cup of pineapple juice into a saucepan and adding 1/2 cup of brown sugar.
Whisk them together until the sugar completely dissolves.
Add 1/3 cup soy sauce, 1/4 cup Jack Daniels whiskey, 1 tablespoon lemon juice, and 1/2 teaspoon cayenne pepper.
Mix the ingredients until they're well combined.
Introduce 1 tablespoon of minced garlic and 1/2 cup diced white onion into the saucepan.
Stir to integrate these aromatics thoroughly.
Bring the mixture to a gentle boil, then reduce the heat to low.
Let it simmer, stirring occasionally until it's reduced by half and thickened.
Once the glaze thickens, remove it from the heat and let it cool to room temperature before using.