Step 1

Melt the butter in a saucepan and remove the saucepan from the heat. Stir in the cocoa and then let everything cool. Meanwhile, blend the eggs and sugar until both are blended. Mix flour, baking powder and salt in another bowl and gradually add it to the egg-sugar mixture. Add the vanilla and cooled cocoa mixture until everything is well-blended.

Step 2

Preheat the oven to 350°F and grease a 13x9-inch baking pan. Bake the brownies for 25 to 28 minutes then insert a toothpick in the center of the brownies to test for doneness (be careful not to overbake these). The toothpick should come out clean. Let the brownies cool on a wire rack.

Step 3

In a large, clean bowl, cream the butter and confectioners sugar until they're light and fluffy, for five to seven minutes. Beat in the cocoa and vanilla extract and then start adding milk. Keep stirring and adding more milk until the frosting is easy to spread. Once the frosting is ready, spread it over the cooled brownies and cut them into bars.