Allow to cool until lukewarm. Add the butter and beat with an electric whisk for 5 minutes. Beat in the icing sugar and then the buttermilk. Place in a piping bag and pipe onto cake.
In this buttermilk coffee cake, the streusel takes a topsy-turvy twist and gets baked ... I suggest wrapping the un-iced cake tightly with plastic wrap or storing it in an airtight container. Top the ...
Was it a gorgeous layered cake with rich chocolate frosting? We doubt it ... Add cocoa mixture in 2 batches, alternating with the buttermilk. Divide batter evenly between pans.