Line the bottom of an 8-inch baking pan with Parchment Paper. Lightly coat the paper and the sides of the pan with vegetable oil. I like to use the Silicone Baking Mats.
Put the sugar in a medium heavy-bottomed pot. Scrape the seeds from the vanilla bean into the pot. Place over medium heat and cook, stirring occasionally with a wooden spoon, just until the sugar melts. Then continue to cook, without stirring, until the sugar turns dark amber, approximately 5 to 6 minutes (to check the color, dab a small amount of the syrup on a white plate). If any crystals form on the sides of the pan as the sugar darkens, wash them down with a wet pastry brush. When the sugar is the correct shade, stir in the corn syrup.
While the sugar is cooking, bring the whipping cream to a boil in a small saucepan over medium heat.
Remove the pot with the hot sugar from the heat and put a sieve or splatter guard over it. Wearing an oven mitt, slowly pour the hot cream into the sugar syrup a little at a time. The mixture will sputter and foam. Be careful, as it is very hot. When the bubbling subsides, return the pan to medium heat and cook, undisturbed, until the mixture registers on 248F. on a cooking thermometer, approximately 5 minutes or when a small amount of sugar syrup is dropped into very cold water, it forms a ball that holds its shape when pressed.
Remove from the heat, immediately add the butter, and stir with the wooden spoon. Add the Fleur de sel salt and stir until evenly distributed. Pour the caramel into the prepared pan and let cool at room temperature.
Invert the pan of cooled caramel onto a work surface. Peel off the parchment paper, if using.
If you are dipping the caramels in chocolate, line a sheet pan with parchment paper. Using a ruler as a guide, cut the caramel square into 1-inch squares with a lightly oiled knife.
Temper the chocolate. Learn How To Melt and Temper Chocolate.
After the chocolate is tempered, dip the caramel squares in the chocolate. Place them on the prepared sheet pan. Sprinkle each square with a few grains of fleur de sel salt before the chocolate sets. When the chocolate has set, store caramels in a cool, dry place, not in the refrigerator.
Makes about 50 pieces.
Fleur de Sel Caramels Recipe: https://whatscookingamerica.net/candy/fleurdeselcaramel.htm