Prep Oven & Pan: Preheat oven to 350°F (175°C). Line a 9x9-inch metal square baking pan with parchment paper, leaving generous overhang on two opposite sides. Spray lightly with nonstick baking spray.

Whisk Fudgy Brownie Batter: In a large bowl, whisk melted butter, granulated sugar, and dark brown sugar vigorously for 1 minute. Add eggs one at a time and vanilla, whisking vigorously for 2 full minutes until the batter turns glossy and pale (this ensures a shiny crinkle base). Fold in cocoa powder, flour, and sea salt with a rubber spatula just until combined. Stir in chocolate chips.

Par-Bake Brownie Base: Spread the thick brownie batter evenly into the prepared pan. Bake at 350°F (175°C) for 18 to 20 minutes, until the top is set but the center remains slightly underbaked.

Simmer Pecan Pie Topping: While the brownies par-bake, combine pure maple syrup (or corn syrup), brown sugar, melted butter, heavy cream, and vanilla in a small saucepan over medium heat. Bring to a gentle simmer for 2 minutes, stirring until sugar is completely dissolved. Remove from heat and stir in all the toasted pecans.

Pour & Finish Baking: Remove the par-baked brownie pan from the oven. Immediately pour the warm caramelized pecan mixture evenly across the brownie surface, spreading gently with an offset spatula. Return to the oven and bake for an additional 20 to 24 minutes, until the pecan topping is bubbling vigorously around the edges and set in the center.

Cool, Sprinkle & Slice: Remove pan and place on a wire rack. Immediately sprinkle with flaky Maldon sea salt. Allow to cool completely to room temperature (approx. 2 hours), or chill for 1 hour for razor-clean slices. Lift using the parchment handles, slice into 16 rich squares, and serve!