Preheat the oven to 350F. Line a square baking pan with parchment paper. In a large mixing bowl, whisk together the sugar, flour, cocoa powder, baking powder and salt.
Mix the oil, eggs, corn syrup and vanilla extract into the dry ingredients. Stir in the hot water. Transfer the batter to the prepared baking pan.
Bake the brownie layer for 20 minutes. While the brownie layer is baking, mix together the brown sugar, corn syrup, vanilla extract, melted butter and eggs.
Mix in the chopped pecans. After the brownie layer has baked for 20 minutes, remove it from the oven and spread the pecan pie layer on top.
Bake for an additional 20 to 25 minutes until the pecan pie filling has set.
Once the brownies are baked, remove the pan from the oven and allow the brownies to fully cool and set, at least one hour, before cutting them into squares.
For best results, transfer them to the fridge once cooled to chill for one hour before cutting.