For the Brownies:

1. Preheat your oven to 350°F (175°C). Grease or line a 9×13-inch baking pan with parchment paper.
2. In a large mixing bowl, whisk together the melted butter, granulated sugar, and light brown sugar until smooth.
3. Add the eggs and vanilla extract, and whisk until fully combined.
4. In a separate bowl, sift together the all-purpose flour, cocoa powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
5. Fold in the semi-sweet chocolate chips.
6. Pour the brownie batter into the prepared baking pan and spread it evenly.
7. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out mostly clean with a few moist crumbs. Let the brownies cool completely in the pan on a wire rack.

For the Caramel Topping:

1. Once the brownies have cooled, drizzle the caramel sauce evenly over the top of the brownies.
2. If using store-bought caramel sauce and it’s not salted, sprinkle the caramel with 1/2 teaspoon of salt to enhance the flavor.
3. Sprinkle the chopped pecans or walnuts on top of the caramel layer, pressing them gently into the caramel for better adhesion.

For the Chocolate Drizzle:

1. Melt the semi-sweet chocolate chips in a microwave-safe bowl or over a double boiler until smooth and fully melted.
2. Drizzle the melted chocolate over the top of the brownies in a crisscross pattern or your desired design.
3. Allow the brownies to cool completely so the caramel and chocolate can set before slicing.