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