Chocolate and Vanilla Marbled Loaf

The main reason for making this cake was a need to use up some sour cream which had been languishing at the back of the fridge - I was determined it wouldn't go to waste and found I had just about the right amount for this recipe.  It also gave me a chance to attempt a recipe from a book I hadn't used before, and as I have a frighteningly fast-growing collection of recipe books, I'm really trying to make sure I actually make use of them all. 

My only concern about the cake was that it doesn't have any icing/topping.  My family, who are generally the lucky(!) recipients of my baking, have a tendency to question the absence of icing on cakes, so I wasn't too sure how that would go down.  I needn't have worried though; reviews were all positive so it must have been very nice cake indeed!  Oddly enough, despite my love of baking, I don't actually have much of an appetite for cakes and biscuits, so I mostly rely on family and friends to taste test.  I only had a small piece, but I did really enjoy the light texture of the cake and the intense flavour of the chocolate mixture.  I have baked marbled cakes before, but it was nice to find one which only makes a small loaf so that we're not left eating it for a week or so!

(recipe from Marks and Spencer 'I Love Sugar' recipe book)

55g dark chocolate

3 tbsp milk

70g unsalted butter

85g caster sugar

1 egg, beaten

3 tbsp sour cream

115g self-raising flour
1/2 tsp baking powder
1/2 tsp vanilla extract

Preheat the oven to 160c, and grease and line a 1lb/450g loaf tin.  Melt the chocolate with the milk over a pan of simmering water, then remove from the heat and leave to cool. 

Cream together the butter and sugar, then beat in the egg and soured cream.  Sift in the flour and baking powder, and fold together lightly using a metal spoon.  Spoon half the mixture into a separate bowl, and stir in the chocolate mixture.  Add the vanilla extract to the plain (non-chocolate) mixture. 

Spoon the chocolate and vanilla mixtures alternately into the prepared tin, swirling together with a skewer for a marbled effect.  Bake in the preheated oven for 40-45 minutes, until well-risen and firm to the touch.  Cool in the tin for 10 minutes, then turn out onto a wire rack.