Put sugar, water, salt and corn syrup in a heavy bottomed medium to large sauce pan. Stir to combine.
Heat over medium heat with out stirring until the caramel turns a deep amber color. Swirl the pan occasionally to ensure even caramelization.
Lower the heat and carefully add the cream.
Stir continuously until mixture has smoothed out.
Insert a candy thermometer and continue cooking the caramel sauce until it reaches 225° F (107° C)
Stir in the vanilla extract until fully combined.
Pour caramel sauce into a heatproof container(s) (glass canning jars are excellent for this) to cool until just warm before using. Store remainder in the refrigerator, warm in the microwave before use.