Combine the sugar, water, and the corn syrup in a large saucepan and stir with a wooden spoon over medium heat until sugar is dissolved.
Cover the saucepan and let it cook over medium heat for 3 minutes.
After 3 minutes, remove the lid, increase the heat to medium-high, and bring to a boil.
Do not stir from this point on, but instead swirl the liquid around the pan so that the caramel doesn’t burn.
Continue to cook until the caramel turns an even amber color then remove from the heat and let stand for about 30 seconds.
*** Be careful here *** Pour the heavy cream into the mixture. The mixture will bubble up significantly and is very hot.
Stir the mixture, again being careful. Add the butter. Stir until combined.
Measure 1 cup into a Pyrex measuring cup. Stirring occasionally, allow to cool until thick like molasses and warm to the touch, about 20 minutes. Save any extra in a sealed container in the refrigerator. It is delicious on ice cream, not to mention your finger…