Preheat oven to 300 degrees. In an electric mixer, cream sugar and shortening. Add eggs and bananas.
Mix well. Sift cocoa, flour, soda and salt. Add alternately with buttermilk while whisking.
Mix in boiling water. Bake in a 13 by 9-inch ungreased pan 50 to 60 minutes.
Cool and cover with frosting.
Frosting:
Combine all ingredients in a saucepan. Cook over low heat, stirring constantly until sauce comes to a boil.
Remove from heat. Add vanilla, and frost cake while icing is hot.
main ingredients: type of recipe:caketype of dish:dessert cuisine:Belgium