Prepare a 9×9 inch or 11×7 inch baking pan by buttering generously or if you have parchment paper just spray lightly with cooking spray and line with parchment paper.
Place sugar, corn syrup, butter, and 1 cup cream in a 4 quart pot and bring slowly to a boil over medium heat, stirring constantly scraping the bottom of the pan with a wooden spoon or heat resistant spatula.
Once it comes to a boil, heat the remaining cup of cream in the microwave for 1-2 minutes until hot (make sure it’s in a big enough bowl so it doesn’t boil over in the microwave). Gradually add the cream in a slow stream to the pot while constantly stirring. You need to add it slow enough that the caramel never stops boiling (if it stops your caramel will become sugary/crystallized).
Stir frequently as the mixture begins to thicken and then stir constantly as it starts to darken. Cook until it reaches 240-242 degrees F. I usually just do the cold water test by spooning a little of the caramel into cold water, let it sit for a few seconds and then pull it out and if it can hold the shape of a ball then it’s done. If not, keep cooking and repeat the test.
Remove from heat and stir in the vanilla. Pour into prepared dish. (Do NOT completely scrape the sides of the pan when pouring the caramel. The caramel that has clung to the sides of the pan is firmer and will make your caramels have ribbons of firmer caramel. Just use a rubber spatula to gently push all the liquid caramel out.) Let the caramels cool completely overnight before cutting.
Cut wax paper strips 5-6 inches long and then cut each strip into thirds to get pieces that are bout 4 inches wide. Cut caramels into squares and place each caramel in the center of a wax paper sheet. Roll up and twist the ends.