For the icing, bring the butter, cream, and brown sugar to a simmer and cook for about 10 minutes, to soft ball stage-238 degrees. Remove from the heat and allow to cool . Transfer to a mixer and beat until cool. Add vanilla, bourbon, and a pinch of salt. Spoon the icing onto the brownies—it should be thick enough to pool up on the brownies without dripping off. If it’s too thin, add a bit of powdered sugar to thicken. If too thick, add warm water, 1 tsp at a time. Sprinkle the iced brownies with Bourbon Smoked sea salt to finish.