Step 1 Bring the half-and-half, butter and fleur de sel to boil in a heavy, 3-quart saucepan. Set aside.
Step 2 Stir together the sugar and corn syrup in a heavy saucepan. Bring to a temperature of 293 degrees on a candy thermometer over medium heat. As the sugar begins to melt, swirl the pan often until all the sugar is melted. Remove the pan from the heat and add the half-and-half mixture. Set the pan over medium heat and bring the mixture to 248 degrees, stirring frequently. This will take 10 to 15 minutes. (The mixture will look like a caramel sauce.)
Step 3Pour into an 8-inch-square nonstick pan and allow to set 2 hours.
Step 4After the caramel has completely cooled, set the pan over very low heat just enough to loosen the caramel, 30 seconds to 1 minute. Invert the pan onto a nonstick surface. Cut the caramel into 36 pieces and wrap individually. Store in a dry place.