Preheat oven to 350°F. Line an 8x8-inch baking pan with foil so the foil extends up and over the sides, then lightly coat the foil with non-stick spray. Set pan aside.

Prepare the 18 oz fudge brownie mix according to the package directions (use the oil, water, and eggs called for on the box). Stir until smooth.

Stir 1/2 cup of the toasted, chopped pecans and 1/2 cup of the semi-sweet chocolate chips into the brownie batter. Pour the batter into the prepared pan and spread into an even layer.

Bake 35 to 40 minutes, or until a toothpick inserted into the center comes out mostly clean. Remove from oven and let the brownies cool completely in the pan on a wire rack.

While the brownies are cooling, set up a double boiler: fill a small saucepan with about 1 inch of water and bring to a gentle simmer. Place a heatproof bowl on top of the saucepan (do not let the water touch the bottom of the bowl).

Place the 20 unwrapped vanilla caramels and 1 tablespoon milk in the heatproof bowl. Stir constantly over the simmering water until the caramels are melted and the mixture is smooth. Remove the bowl from the heat.

Pour the warm caramel evenly over the cooled brownies. Immediately sprinkle the remaining 1/2 cup chopped pecans over the caramel.

Wipe or replace the bowl, set it over the simmering water again, and add the remaining 1/4 cup semi-sweet chocolate chips. Stir until the chocolate is melted and smooth. Remove from heat and drizzle the melted chocolate over the caramel layer.

Let the brownies stand at room temperature until the toppings are set, about 2 hours. Use the foil overhang to lift the brownies from the pan, slice, and serve.