Line a 6 x 8 or 8 x 8 inch pan with parchment; set aside.
Combine all ingredients except vanilla in heavy 4-quart saucepan. Cook over medium heat, stirring occasionally, 15-20 minutes or until butter is melted and mixture comes to a boil.
Continue cooking without stirring, 25-30 minutes or until candy thermometer reaches 244°F (or to 248°F for a slightly firmer caramel) or small amount of mixture dropped into ice water forms a firm ball.
Remove from heat; stir in vanilla. Pour into prepared pan. Cool.
When the caramel is cool, lift the sheet from the pan onto a cutting board. Cut the square in half.
Starting with a long side, fold the caramel up tightly into an 8-inch-long log.
Sprinkle the log with fleur de sel, trim the ends and cut into pieces. Try brushing the knife with flavorless oil or spraying with non-stick spray if you are having problems with sticking.
Wrap the candies individually and store in the refrigerator. Take out to warm before serving.
Notes
The calorie count is based on smaller (cut into 32) pieces of caramel.An often cited alternative to the corn syrup is to use 1/4 cup maple syrup plus 1 teaspoon lemon juice. This version was delicious for a couple days, but it crystalized in less than a week. Otherwise I believe that Golden Syrup (Britain's answer to corn syrup, but made with sugar not corn) should work but I haven't tried it.Adapted from Ina Garten & Land o' Lakes
I am not a health professional and nutrition data is calculated programatically. Accuracy may vary with product selection, calculator accuracy, etc. Consult a professional for the best information.