Preheat the Oven:
Preheat your oven to 350°F (175°C). Grease a 9×9-inch baking pan or line it with parchment paper.

Prepare the Brownie Base:
In a medium-sized bowl, whisk together the melted butter and granulated sugar until smooth. Add the eggs one at a time, whisking well after each addition, then mix in the vanilla extract.

Combine Dry Ingredients:
In another bowl, sift together the flour, cocoa powder, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, stirring until just combined. The batter will be thick.

Assemble the Brownies:
Pour the brownie batter into the prepared pan and spread it out evenly. Set aside.

Prepare the Pecan Pie Topping:
In a medium saucepan over medium heat, combine the corn syrup, brown sugar, melted butter, and vanilla extract. Stir until the sugar is dissolved, then remove from heat.

Add Eggs and Pecans:
Whisk in the eggs one at a time, making sure the mixture is smooth. Fold in the pecan halves.

Assemble and Bake:
Pour the pecan mixture over the brownie base, spreading it evenly with a spatula. Bake in the preheated oven for 30-35 minutes or until the center is set but still slightly soft (a toothpick inserted should come out with a few moist crumbs).

Cool and Slice:
Allow the brownies to cool in the pan for at least 30 minutes before slicing into squares. The longer you let them cool, the easier they’ll be to cut.