Preheat oven to 350° F. Line a 9x13-inch baking dish with foil and spray foil with non-stick spray. Set aside.
In the bowl of an electric stand-mixer, add the melted butter and cocoa powder. Using the paddle attachment, blend until smooth.
Add the flour and sugar. Beat together then add eggs and vanilla. Mix just until combined. Don't over mix. (Batter will be thick)
Pour batter into prepared baking dish and spread out evenly. Bake 25 to 30 minutes or until toothpick inserted in center comes out clean. Remove brownies from oven and let stand 15 minutes before frosting. You want the brownies still warm when you frost them!