Preheat oven to 350 degrees. And lightly grease a 9 x 13" pan.
In a large bowl, add 4 eggs, and beat with cocoa, salt, baking powder, and vanilla. Stir until combined and smooth.
In a medium-sized microwave-safe bowl, or in a saucepan set over low heat, melt the butter, then add the sugar and stir to combine.
Add the warm butter/sugar mixture to the egg/cocoa mixture, stirring until smooth. Make sure the butter mixture is warm but not too hot or it will scramble your eggs.
Add the flour and chocolate chips to the batter and stir until fully incorporated.
Spread batter into prepared pan and smooth as needed.
Bake brownies about 30 minutes. Test for doneness by inserting a toothpick in the center of the brownies and making a little divit so you can see the center a bit. You should find moist crumbs but no wet batter. Remove from the oven and cool on a rack before cutting and serving.