combine brown sugar, syrup butter, and salt in a saucepan on the stovetop over medium heat.
Add water and stir, then bring to a simmer. Cook (swirling the pan occasionally ) for about 12-15 mins, until it reaches a deep brown color and thick enough to drip off of a spatula.
Meanwhile, combine the cream and cornstarch in a small bowl. Remove the glaze from heat, and slowly add to the caramel.
Return pan to heat and stir frequently, cooking an additional 5 minutes. Remove from heat and stir in the liquor (or vanilla).
Let stand, stirring occasionally, for 30 minutes. The caramel with being thick and slightly warm.