Prep the pan: Line an 8-inch-square baking pan with parchment paper, allowing it to drape over 2 sides, then brush the paper lightly with oil.

Boil the sugar: In a deep saucepan (6 inches wide and 4 1/2 inches deep), combine 1/4 cup water, the sugar and corn syrup and bring them to a boil over medium-high heat. Boil until the mixture is a warm golden brown. Dont stir -- just swirl the pan.

Heat the cream: In the meantime, in a small pot, bring the cream, butter and 1 teaspoon of fleur de sel to a simmer over medium heat. Turn off the heat and set aside.

Finish the caramel: When the sugar mixture is done, turn off the heat and slowly add the cream mixture to the sugar mixture. Be careful -- it will bubble up violently. Stir in the vanilla with a wooden spoon and cook over medium-low heat for about 10 minutes, until the mixture reaches 248 degrees F (firm ball) on a candy thermometer.

Fill the pan: Very carefully (its hot!) pour the caramel into the prepared pan and refrigerate for a few hours, until firm.

Cut the caramel: When the caramel is cold, pry the sheet from the pan onto a cutting board. Cut the square in half.

Roll it up: Starting with a long side, roll the caramel up tightly into an 8-inch-long log.

Cut into pieces: Sprinkle the log with fleur de sel, trim the ends and cut into 8 pieces. (Start by cutting the log in half, then continue cutting each piece in half until you have 8 equal pieces.) Its easier to cut the caramels if you brush the knife with flavorless oil like corn oil.

Wrap the candies: Cut glassine or parchment paper into 4-by-5-inch pieces and wrap each caramel individually, twisting the ends. Store in the refrigerator and serve the caramels chilled.