01 - Heat sugar in a medium heavy-bottomed saucepan over medium heat. Stir constantly with a heat-resistant spatula or wooden spoon as the sugar melts, clumps, then transforms into golden-brown liquid.
02 - Once sugar reaches deep amber color, carefully add butter cubes. The mixture will bubble vigorously—keep stirring until butter melts completely and incorporates into the caramel.
03 - Slowly pour in heavy cream while stirring. The mixture will bubble up again; continue stirring until sauce becomes smooth and fully combined.
04 - Remove from heat immediately. Stir in salt and vanilla extract. Allow sauce to cool for 10–15 minutes before serving; the caramel will thicken as it cools.