Preheat oven to 325 and line 9×13" cake pan with parchment paper. Set aside.
Melt butter in heat proof bowl, add sugar, baking chocolate, half the chocolate chips and vanilla. Whisk until combined and let sit for 10 mins.
In another mixing bowl combine flour, baking powder, cocoa powder and salt and whisk for 30 seconds or until no clumps of cocoa powder remain. A flour sifter can also be used as an alternative. Set aside.
Add eggs one at a time to the butter, sugar and vanilla mixture and mix until combined using the whisk.
Add in flour mixture and fold in using spatula until combined. Don't over mix or you will have tough brownies.
Pour brownie mixture into parchment lined 9×9" cake pan.
Cook in pre-heated oven for 35-40 minutes until top is soft but not jiggly. Toothpick should come out mostly clean. Caution: chocolate can burn easily so don't overcook!
Let cool for 1 hour min. before cutting. For best results, let cool for 30 mins, then finish cooling in fridge for 1-12 hours, then cut.