In a heavy saucepan, stir together granulated sugar, corn syrup, and water. Stir until combined.
Place the saucepan over medium heat and bring the mixture to a simmer. During this time, stir the mixture to ensure that the sugar dissolves evenly and completely as it heats.
Use a pastry brush dipped in water to wash down the sides of the pan, making sure that no sugar crystals remain stuck to the pan above the line of the mixture.
Once the mixture comes to a simmer and the pan has been washed down, do not stir any longer.
Place a candy thermometer in the sugar mixture and monitor it as it heats until the color turns amber and the candy thermometer has reached about 355-360°F.
Remove the caramelized sugar from the heat and slowly stir in the cream, taking care as the mixture will splatter.
Stir in the vanilla extract and then the pieces of butter, 2 tablespoons at a time.
Cool to room temperature.