Preheat oven to 350°F. Line a 9-inch baking dish with parchment paper. Set aside.
In a medium sized saucepan, melt butter over medium heat. Remove from heat and add in chocolate chips and sugar.
Stir until chocolate is completely melted. Add in eggs, one at a time, stirring completely after each addition. Stir in vanilla.
Add the cocoa powder, flour, salt, and baking powder. Using big strokes, stir in JUST until mixed and no longer see dry ingredients. DO NOT BEAT OR OVER STIR.
Pour batter into dish and bake for about 20 minutes. While the brownies are baking, make the pecan pie topping.
In a medium bowl, whisk the corn syrup, maple syrup, and brown sugar together. Add the egg and vanilla extract and whisk until combined.
Add in the pecans, and stir with a spatula until the pecans are coated with the syrup mixture.
Spread the pecan mixture over the partially baked brownies, then bake for another 25-30 minutes, or until a small knife poked in the middle of the brownies comes out mostly clean.
Set the brownies on a cooling rack, and cool completely. Slice and serve.
Notes
Substitutions: Salted butter can be used in place of unsalted. Boxed brownie mix could be used (but our homemade version is so easy). Dark corn syrup can be used in place of the light corn syrup. Light brown sugar can be used in place of the dark brown sugar.