Preheat oven to 350℉. Line a 9x13 pan with enough parchment paper so that two ends drape over the side.
In a medium mixing bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.
Using an electric mixer and separate mixing bowl, beat together the softened butter and sugar at medium speed for 3 minutes or until creamed together. Add eggs one at a time beating well between each egg. Then add the vanilla extract.
Gradually add in the flour mixture at a low speed, beating just until blended.
Spread the very thick batter in the prepared 9x13 pan. Do the best you can to spread it to the sides of the pan. You may need to hold onto the parchment paper while you spread.
Sprinkle the top with chocolate chips and chopped pecans.
Bake for 30 minutes or until a toothpick inserted in the center comes out almost clean. Cool in the pan for 5 minutes. Then, using the sides of the parchment paper, lift the brownies out of the pan and let it cool on a wire cooling rack.
Once the brownies are cooled completely, cut into generous brownies. These are great by themselves, or with ice cream, or topped with whipped cream.