Preheat oven to 350° F. Grease a 9×13-inch baking pan and line with parchment paper, leaving some parchment paper hanging over the edges for easy removal.
Prepare dry ingredients: In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt. Set aside.
Make wet mixture: In a large bowl, whisk together melted butter and sugar until well combined and smooth, about 1 minute. Add eggs one at a time, whisking well after each addition. Stir in vanilla extract.
Combine: Add the dry ingredients to the wet ingredients and fold gently with a spatula until just combined. Do not overmix—a few streaks of flour are okay. Fold in chocolate chips until evenly distributed.
Bake: Pour batter into the prepared pan and spread evenly with a spatula. Bake for 23-25 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs (not wet batter). Do not overbake.
Cool completely: Let brownies cool in the pan on a wire rack for at least 1 hour. The brownies must be completely cool before cutting into shapes.