Place the brown sugar, butter, and heavy cream into a small saucepan. Over medium-low heat, bring the mixture to a boil, stirring constantly. Boil for approximately 1 to 2 minutes. Remove the pan from the heat and stir in the salt.
Allow the caramel to cool and thicken before using.
After the caramel has cooled completely, store it in an airtight container in the refrigerator for up to 2 weeks.