Prepare an 8 by 8-inch square baking pan by lining it with foil, allowing the foil to extend over the pan sides for easy removal. Spray with non-stick cooking spray.
Combine the cookie crumbs and melted butter in a mixing bowl; stir together until all the crumbs are moistened and the butter has absorbed into the crumbs (they should have the consistency of wet sand). Spoon them into the prepared pan and press down to form a firm, flat bottom layer. Tip: I used a heavy, flat meat tenderizer to evenly compress the crumb layer.
Place in the refrigerator to cool fully; approximately 20 minutes.
Place the unwrapped caramels and the cream in a small, heavy saucepan over medium low heat. Stir constantly to allow the caramels to fully melt.
Using a heatproof silicon spatula, scrape the melted caramel onto the cookie crumb layer in the pan and smooth to an even thickness. Cover and place back into the refrigerator to fully cool; about 30 minutes. Note: this cooling cycle is important to ensure the caramel and chocolate layers do not mix together.
Once the caramel layer has cooled, place the chocolate chips and tablespoon of butter in a small bowl. Follow the instructions on the chocolate chip package to melt the chocolate either in the microwave or in a double boiler on the stovetop. Stir briskly to fully mix the chocolate chips and butter to a smooth consistency.
Spread onto the caramel layer and smooth the top. Tap the pan multiple times on a firm surface to allow the chocolate to form a uniformly thick layer. Sprinkle lightly with Fleur de Sel and allow to sit at room temperature for 10 minutes before covering and placing in the refrigerator to fully cool and harden.
Remove the pan from the refrigerator and using the overhanging foil, remove the bars from the pan. Allow them to sit at room temperature for 5-10 minutes to warm slightly. Cut into bars and store in the refrigerator.