Mix brown sugar and butter in a saucepan on medium heat until melted.
Add a pinch of salt and 4 ½ tablespoons of heavy cream, whisk together, and use a candy thermometer for accuracy.
Let the caramel boil, whisking until it hits 110°C or 230°F.
Remove from heat, whisk once, and let it cool for 1 to 2 minutes. Transfer to a heat-tolerant bowl on a cooling rack for 20 minutes to thicken.
Add confectioners’ sugar and 3 tablespoons of heavy cream. Blend with a handheld or electric mixer on high for a minute. Adjust consistency with extra cream, but don't overmix.
If piping, let your caramel icing cool for 20-30 minutes for the perfect consistency.