Preheat your oven to 350°F (175°C). Line a 9x9-inch metal baking pan with parchment paper, leaving some overhang on the sides to use as handles later. Grease the parchment and any exposed parts of the pan.
Prepare and bake the brownies according to the package directions for a 9x9-inch pan. Once baked, let the brownies cool completely in the pan on a wire rack. This may take about an hour.
While the brownies cool, make the topping. In a medium bowl, stir together the chopped pecans, melted butter, brown sugar, corn syrup, honey, heavy cream, and salt until everything is well combined.
Pour the pecan mixture over the top of the completely cooled brownie base. Use a spatula to spread it into an even layer, making sure it reaches all the edges.
Place the pan back in the oven and bake for 20 minutes, or until the topping is bubbly and slightly browned around the edges.
Remove the pan from the oven and let it cool completely on a wire rack. Then, transfer the pan to the refrigerator and chill for at least 2 hours. This step is important to help the topping set.
Once chilled, use the parchment handles to lift the entire slab of brownies out of the pan. Place it on a cutting board, slice into 16 squares, and sprinkle with flaky sea salt before serving. Drizzle with caramel sauce, if you like.