Preheat oven to 350 degrees.
Grease and flour a 10 ½ x 15 ½ x 1 inch jelly roll pan.
In a large mixing bowl, combine butter, cocoa, sugar, eggs and vanilla. Blend well.
Stir together flour, salt and baking powder. Stir into cocoa mixture until smooth.
Add black walnuts and mini kisses.
Spread evenly in the prepared pan and bake 25 minutes on middle oven rack.
Cool before cutting.