Step 1: Prepare the crust. In a food processor, finely crush the chocolate wafer cookies until they resemble fine crumbs. Alternatively, place cookies in a resealable bag and crush with a rolling pin. Transfer crumbs to a medium bowl.
Step 2: Add 1/2 cup melted butter to the cookie crumbs and mix until well combined. Press the mixture firmly and evenly into the bottom of a 9x13 inch baking dish lined with parchment paper, leaving an overhang on the sides for easy lifting. Chill in the refrigerator for at least 30 minutes.
Step 3: Prepare the caramel layer. Spread the dulce de leche evenly over the chilled cookie crust. Sprinkle with 1/2 teaspoon of flaky sea salt. Return to the refrigerator to chill for another 30 minutes.
Step 4: Make the chocolate ganache. In a medium heatproof bowl, combine the chocolate chips and 1 tablespoon of butter. In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer around the edges (do not boil).
Step 5: Pour the hot cream over the chocolate chips and butter. Let it sit undisturbed for 5 minutes, then whisk gently until smooth and glossy. If necessary, you can microwave it for a few seconds and whisk again until fully melted and smooth.
Step 6: Pour the chocolate ganache evenly over the chilled caramel layer. Gently spread to cover the entire surface. Sprinkle the remaining 1/2 teaspoon of flaky sea salt over the ganache.
Step 7: Chill the dessert. Refrigerate for at least 3-4 hours, or preferably overnight, until the ganache is completely set and firm. Once firm, use the parchment paper overhang to lift the dessert out of the pan and place it on a cutting board.
Step 8: Slice and serve. Use a sharp knife, wiping it clean with a warm, damp cloth between each cut, to slice the dessert into squares or bars. Serve chilled and enjoy!