Preheat the oven to 180 C / Gas 4. Grease and line a 900g loaf tin with baking parchment.
In a large bowl, combine the butter and sugar and beat until smooth with an electric whisk. Add the eggs, one at a time, whisking well after each addition. Sift in the flour then add the baking powder, milk and vanilla extract. Whisk until thick and creamy. Mix in the melted chocolate and beat until mixture is smooth. Pour into the prepared loaf tin and smooth the top.
Bake in the oven for 80 to 90 minutes, or until a skewer inserted into the centre comes out clean. Remove from the oven and cool to serve cold, or enjoy warm from the oven.
Lovely cake but way too much mixture for one loaf tin, next time will bake it in a bigger tin. I added almond essence instead of vanilla, v tasty. Also drizzled white choc over the top of the cake when it cooled. Will make this again. - 09 Jan 2015