**Preheat Oven:** Preheat your oven to 350°F (175°C) and line a 9x13-inch baking pan with parchment paper, leaving an overhang for easy removal.
**Make Brownie Batter:** In a large mixing bowl, whisk together melted butter, granulated sugar, and brown sugar until smooth. Add the eggs one at a time, mixing well after each addition. Stir in vanilla extract.
**Combine Dry Ingredients:** In a separate bowl, whisk together flour, cocoa powder, baking powder, and salt. Gradually fold the dry ingredients into the wet ingredients until just combined.
**Prepare Caramel Layer:** In a saucepan over low heat, gently heat the caramel sauce or melted caramel candies with heavy cream, stirring until smooth and pourable.
**Layer the Brownies:** Spread half of the brownie batter evenly into the prepared pan. Pour the caramel mixture over the top, spreading it out evenly. Sprinkle with chocolate chips and pecans, if using. Carefully spread the remaining brownie batter over the caramel layer.
**Bake:** Bake in the preheated oven for 35–40 minutes, or until the edges are set and a toothpick inserted into the center comes out with a few moist crumbs.
**Cool and Serve:** Allow the brownies to cool completely in the pan before lifting them out using the parchment paper. Slice into squares and serve.