- Preheat oven to 180C (160C fan/ Gas Mark 4). Grease and line two 20cm (8 inch) round cake tins. 
- In a large bowl, cream together the softened butter and granulated sugar until light and fluffy. 
- Beat in the eggs one at a time, then stir in the vanilla extract. 
- In a separate bowl, whisk together the self-raising flour and cocoa powder. 
- Gradually add the dry ingredients to the wet ingredients, alternating with the milk, beginning and ending with the dry ingredients. Mix until just combined. 
- Stir in the melted dark chocolate until evenly distributed. 
- Pour the batter evenly into the prepared cake tins. 
- Bake for 30-35 minutes, or until a skewer inserted into the center comes out clean. 
- Let the cakes cool in the tins for 10 minutes before transferring them to a wire rack to cool completely. 
- For the Fudge Icing: In a large bowl, beat together the butter, icing sugar, and cocoa powder until smooth. Gradually add the milk, mixing until combined. Stir in the melted dark chocolate. 
- Once the cakes are completely cool, spread a layer of fudge icing over one cake layer, top with the second cake layer, and frost the entire cake with the remaining icing. 
- Slice and serve. 
- Optional Tips: For a richer flavour, substitute strong brewed coffee for the milk in the cake batter. Chopped nuts or chocolate chips can be added to the batter for added texture. If self-raising flour is not available, use plain flour and add 2 teaspoons of baking powder.