Preheat oven to 350F degrees. Line 13x9 inch baking pan with foil, leaving a 2-inch overhang on two sides; coat the foil with cooking spray. Set aside
Using a electric or stand mixer, cream butter and sugar together.
Add eggs and vanilla.
In a medium bowl, combine flour, cocoa powder, baking powder and salt.
Add dry ingredients to creamed mixture and mix until just combined. DO NOT OVERMIX!
Pour brownie batter into prepared pan. Top with chocolate chips and walnuts.
Bake for 35-40 minutes or until a toothpick inserted into the center of the brownies comes out clean. Let cool before cutting brownies into squares.
Notes
LINE YOUR BAKING PAN: First things first, line your 13×9 inch baking pan with aluminum foil, leaving enough overhang on the sides. Spray the foil with non-stick cooking spray.
DON’T OVER MIX THE BROWNIE BATTER: This is super important because if you overmix the brownie batter, you will have super dense, not so delicious brownies. So when you add the dry ingredients (flour, cocoa powder, baking soda and salt) to the creamed mixture (butter, sugars, eggs and vanilla), you only want to mix it until just combined meaning the second you don’t see anymore flour you want to stop mixing.