Preheat the oven to 350° F. Grease a 9x13-inch pan** with butter or line with parchment paper. In a large bowl, whisk together the melted butter and sugar. Make sure the butter mixture is almost room temperature and then add the eggs and vanilla.
Beat until well incorporated. Beating in the eggs well is what forms that signa mture brownie crust on top.
Add the flour, cocoa, baking powder and salt. Whisk until incorporated. Pour the batter into the prepared pan. Bake at 350° F for 28-32 minutes or until center is set. Let cool at least slightly before cutting into bars.
