Make the brownies: Preheat the oven to 350 degrees F.
Line an 8-inch square baking dish with a sheet of aluminum foil, making sure to cover the corners and sides. Lightly butter the aluminum foil, including corners and sides.
In the bowl of a double boiler set over simmering water, combine the butter and chopped unsweetened chocolate. Stirring often, heat until melted and smooth. Remove from the heat and stir in the sugar and salt. Add the eggs and vanilla and stir until well blended. Fold in the sifted flour and stir just until the flour disappears. Stir in the semisweet or bittersweet chocolate chunks.
Pour the batter into the prepared baking dish and spread evenly. Bake approximately 30 minutes or until a toothpick inserted into the center comes out clean. Baking time will be longer if you are using a metal pan. Do not overbake. Transfer the dish to a wire rack and cool completely.
Make the Carmel-Cashew Topping: Pour the cream into the bowl of a double boiler set over simmering water. Unwrap caramels and put them into the bowl. Stirring frequently to prevent sticking, combine the cream and caramels until the mixture becomes homogeneous and smooth. Take the mixture off the heat and keep stirring until the caramel becomes a little thicker and the mixture begins to cool down. Add a pinch of salt and the vanilla and stir. Coarsely chop the cashews and fold them into the caramel mixture until nuts are completely coated with caramel. Pour mixture over the top of the cooled brownies and spread evenly.
Refrigerate the brownies until the caramel is set, about 30 to 45 minutes. Remove brownies from the pan by grabbing the sides of the aluminum foil and lifting them from the pan. With a serrated knife, cut the brownies into 2-inch squares. These can be stored in an airtight container for 2 days or in a covered container in the refrigerator for 4 days.