Stir in the cocoa, salt, baking powder, and vanilla. Add the eggs, beating till smooth; then add the flour and chips, beating until well combined. Spoon the batter in the prepared pan. Bake the brownies for 28 - 30 minutes, until a cake tester inserted into the center comes out dry (though it may have a few crumbs clinging to it). The brownies should feel set both on the edges and in the center. Remove them from the oven and after 5 minutes, loosen the edges with a table knife; this helps prevent the brownies from sinking in the center as they cool. Cool completely before cutting and serving. ENJOY!