Preheat oven to 350 degrees F (175 degrees C). Grease and flour an 8-inch square pan.
In a large saucepan, melt 1/2 cup butter. Remove from heat, and
stir in sugar, eggs, and 1 teaspoon vanilla.
Beat in 1/3 cup cocoa, 1/2 cup flour, salt, and baking powder. Spread batter into pre
pared pan.