I have no doubt that the last thing anyone wants to see on the day after Halloween is a recipe for another sweet treat. But rest assured, this in a different league than the individual-sized pre-packaged treats you have been smuggling all day from your children's plastic pumpkins. This is a sophisticated, gourmet recipe. One that uses the flawless combination of salty and sweet and just when you think it can't get any better, the salty flavor comes from one of the most coveted and elegant salts around, Fleur de Sel. Chocolate-Caramel Cookie Bars
Martha Stewart Living November 2009
For the Crust:
4 1/2 ounces (9 tablespoons) unsalted butter, room temperature, plus more for parchment
1/4 cup packed light-brown sugar
1 1/2 cups all-purpose flour
1/4 teaspoon table salt
For the Chocolate Caramel:
10 1/2 ounces milk chocolate, chopped (2 cups)
1 1/2 cups granulated sugar
1/4 water
3 ounces (6 tablespoons) unsalted butter
1 cup heavy cream
1/2 teaspoon table salt
1 tablespoon sea salt, preferably fleur de sel
1. Preheat oven to 350 degrees. Make the crust: Line a 9-inch square baking pan with parchment, leaving an overhang on all sides, butter parchment, excluding over-hang. Beat butter and brown sugar on medium speed until pale and fluffy, about 3 minutes. Add flour and table salt, and beat until just combined.
2. Press dough evenly into pan, and bake until lightly browned, about 30 minutes.
3. Make the chocolate caramel: Place chocolate in a medium bowl. Heat granulated sugar and water in a small saucepan over medium-high heat (stirring only once to mix the two ingredients and letting it do the work on its own after the initial stir), washing sides of pan with a wet pastry brush to prevent sugar crystals from forming,
until amber, 10-12 minutes. Remove from heat.
Add butter, cream and table salt (be very careful during this step as the caramel will bubble when you add these ingredients). 
Bring to a boil, stirring until smooth. Pour over chocolate. Let stand for 2 minutes.
Stir to combine, and let stand until cool, about 10 minutes.4. Pour mixture over crust.
Refrigerate at least 4 hours, or overnight. Run a knife around edges; lift parchment to remove whole bar from pan. Sprinkle with sea salt. Trim edges and cut into 16 bars using a sharp knife that has been sitting in a glass of hot water. Be sure to clean the knife in the hot water and remove the crust from the blade between cuts to ensure a smooth outer edge on the bars. Bars can be refrigerated for up to 3 days.
