For the shortbread layer:?2 cups all-purpose flour?2 tsp. baking powder?¼ tsp. salt?1 cup (2 sticks) unsalted butter, at room temperature?½ cup sugar
•
For the caramel layer:?1 cup (2 sticks) unsalted butter, cut into pieces?1 cup sugar?4 tbsp. light corn syrup?2 (14 oz.) cans sweetened condensed milk
•
For the chocolate layer:?8 oz. semisweet or bittersweet chocolate, finely chopped?1 tsp. light corn syrup?½ cup (1 stick) unsalted butter, cut into pieces?Fleur de sel or sea salt, for sprinkling