Preheat your oven to 350°F (175°C). Grease a 9x13 inch baking pan or line with parchment paper.
In a large bowl, whisk together melted butter, granulated sugar, brown sugar, eggs, and vanilla until smooth.
In another bowl, sift together cocoa powder, flour, baking powder, and salt.
Gradually fold dry ingredients into the wet mixture until just combined; do not overmix.
Pour batter into the prepared pan and spread evenly. Bake for 25-30 minutes until a toothpick comes out with moist crumbs.
Allow brownies to cool in the pan for at least ten minutes before cutting into squares.
