black forest mud cake

This easy, mix and bake black forest mud cake very good for any occasion.
Ingredients:
1. 200g (7 oz) (45%) chocolate, chopped
2. 300g (10.5 oz) unsalted butter, chopped, softened
3. 500g (17.6 oz) sour cream, at room temperature
4. 1 cup (150g) self-raising flour, sifted
5. 1 cup (150g) plain flour
6. 100g (3.5 oz) cocoa, sifted
7. 5 eggs, at room temperature, lightly beaten
8. 250g (8.8 oz) caster sugar
9. 200g (7 oz) brown sugar
For the chocolate frosting:
1. 250g (8.8 oz) unsalted butter, chopped, softened
2. 2 2/3 cups (320g) icing sugar, sifted
3. 1 tsp vanilla extract
4. 3/4 cup (75g) cocoa powder, sifted
For decoration:
1. 1 bar (80g) of chocolate ripe chocolate, cut on small sizes
2. Small amount of double cream
Method:
1. Preheat oven to 320F (160C). Spray a 20cm (8 inch) deep round baking tin with non-stick cooking spray and line with non-stick baking paper.
2.