Preheat your oven to 325 degrees F (165 degrees C). Line an 8x8-inch baking pan with parchment paper, leaving some hanging on the sides, and give it a light oiling.Chef's Note: If you're using a 9x9-inch pan, keep an eye on the baking time—it might be a bit quicker. Now, onto the brownie batter. In a mixing bowl, blend white sugar, cocoa powder, kosher salt, and that luscious melted butter. Mix it up; it might look grainy, but that's totally cool.
Add vanilla and one egg, mix again until combined. Toss in the second egg, blend until you have a smooth, glossy batter. Slowly add the flour, mix until it disappears, and spread the batter evenly in the prepared pan. Give it a little tap on the counter to level it out.
Bake the brownie base for 20 minutes, then let it cool on a wire rack while we whip up the pecan pie filling.
Bump up the oven temperature to 350 degrees F (180 degrees C).
For the pecan pie filling, whisk together brown sugar, salt, vanilla, corn syrup, eggs, and melted butter until smooth. Stir in those glorious chopped pecans.
Pour the pecan pie filling over the brownie base, spread it evenly, and give the pan a gentle tap to level it out.
Back in the oven it goes, and this time it's for about 1 hour. You'll know it's ready when the pecan pie filling is almost fully set, with just a slight jiggle in the center if you give it a gentle shake.
Let it cool for about 30 minutes, but for the best results, cover and chill before cutting. Lift those brownies out using the parchment paper overhang and cut them into 16 perfect 2x2-inch squares.