Makes sufficient to fill and frost a 9" round layer cake or a 9x13x2" rectangular cake.
1/4 cup butter
1/2 cup cocoa
1/2 tsp. vanilla
3 cups icing sugar
1/4 cup mashed ripe banana
2 tbsp milk
Melt butter in a saucepan; stir in cocoa and vanilla.
Blend in icing sugar, banana and milk until smooth and of spreading consistency.