Combine cream, sugar, corn syrup and butter in a large stock pot and bring to a low boil.
Stir frequently to prevent the mixture from boiling up and over the pot.
Continue to cook for about 20 minutes before turning up the heat just a bit. Mixture will turn thick and more amber in color.
Continue to cook and stir until candy thermometer reaches 248 degrees. This will probably take about 35-minutes.
NOTE: If the temperature exceeds 248 degrees, you may end up with a much harder caramel. Also, if you want a softer caramel (that you can roll), remove from stovetop at about 246-247 degrees.
Carefully pour the mixture evenly into prepared pan.
Lightly and evenly sprinkle the surface of the caramel with a wee bit of sea salt.
Allow the candy to cool in the pan for about 6-8 hours, or overnight.
Once candy is completely cool and hard, use a knife to loosen caramel along edges of pan.
Turn caramel sheet out of pan and parchment paper and onto a large cutting board.
Carefully cut into bite-size squares. I like to cut the candy into strips and then, cut the strips into squares.