Chocolate satin icing
1.Preheat oven to 180ºC (160ºC fan-forced). Grease 26.5cm x 36.5cm baking dish; line base and long sides with baking paper, extending paper 5cm over sides.
2.Combine cake mix, oil, the water, chocolate, sugar, eggs and sifted dry ingredients in large bowl; beat on low speed with electric mixer until ingredients are combined. Increase speed to medium; beat about 3 minutes or until mixture is smooth and paler in colour. Stir in cherries. Pour mixture into dish.
3.Bake about 1 hour 20 minutes. Stand cake in dish 10 minutes before turning, top-side up, onto wire rack to cool.
4.Meanwhile, to make chocolate satin icing, stir chocolate and butter in small saucepan over low heat until smooth. Stir in sour cream. Refrigerate 5 minutes or until icing is spreadable.
5.Spread cake with icing.