4 tbsps butter or margarine
1/4 cup cocoa powder
1/4 cup buttermilk
1 tsp vanilla essence
2 1/4 cups sifted powdered sugar
In saucepan,combine first 3 ingredients;bring to boiling(mixture may appear slightly curdled)
Remove from heat.Stir in vanilla essence and sifted powdered sugar;
immediately pour over brownies;spread to edges.