Hedgehog cake

Name: Hedgehog cake
Prep time: 1 h 30 min
Cook time: 1 h
Total time: 2 h 30 min
Cuisine: European
Ingredients: 150g unsalted butter, plus extra for greasing; 150g plain chocolate, broken into pieces; 150g plain flour; ½ tsp baking powder; ½ tsp bicarbonate of soda; 200g light muscovado sugar; 2 large eggs; 150g soured cream; 1 tsp vanilla extract; 2 tbsp cocoa powder; 2 tbsp hot water; 150g unsalted butter, softened; 300g icing sugar, sieved; 2 x 134g boxes chocolate Flake bars; 2 chocolate chips; 2 gold or silver balls; 1 round chocolate