* Preheat oven to 350º.
* Prepare either a 9 by 9 inch or an 8 by 8 inch baking pan by lining it with parchment paper leaving excess hanging over two sides.
* Melt butter in medium saucepan over medium-low heat. Remove from heat. Stir in sugar and chocolate chips. Stir until mixture is smooth.
* Add eggs one at a time, mixing between additions. Then add vanilla.
* In a separate bowl, mix cocoa powder, flour, salt and baking powder. Add dry ingredients to the saucepan and mix together. Do not over mix. When there are still a few small lumps of unmixed flour and cocoa powder visible, stop mixing.
* Pour the batter into the prepared baking pan.
For 9 by 9 pan, Bake 32 - 38 minutes
For 8 by 8 pan, Bake 48 - 55 minutes.
* Allow the brownies to cool completely (this will take several hours), and then lift them out of pan using parchment paper. Cut into bars.