How to Make It
Preheat oven to 325°F. Grease a 9- x- 13-inch metal baking pan with cooking spray and line the bottom with parchment paper; set aside.
Make Brownie Batter: Melt butter in a saucepan over medium-high. When butter begins to boil, remove from heat and add chocolate chips, stirring once to coat. Allow to sit for 5 minutes before whisking together until fully combined. In a large mixing bowl, whisk together brown sugar, granulated sugar, eggs, vanilla, and salt. Add chocolate mixture and whisk to combine. Sift cocoa powder and flour into wet ingredients and gently stir until fully incorporated. Pour batter into prepared pan and bake until a toothpick inserted in the center comes out clean, about 35 minutes.
Make Pecan Pie Topping: While brownies are baking, whisk together brown sugar, eggs, vanilla, salt, and melted butter until everything is well combined and the sugar is dissolved. Stir in pecans and set aside.
Once the brownies are baked through, pour the pecan mixture overtop the brownies and spread evenly with a spoon. Return to the oven until the Pecan Pie Topping is set, about 25 minutes. Allow to cool completely before slicing.