Chocolate orange and vanilla marble cake

May I introduce a little adaptation (I was going to say invention, but that's taking it a little far) all of my own? As you've probably realised if you're a regular reader, I tend to like my cakes to have strict recipes, which I tend to largely observe. However, I had a combination of ingredients to use up this past weekend that required a little creativity on my part.

Having enjoyed the chocolate orange combo in this cake recently, I wanted to repeat it, but wanted to make a much larger cake, and I also needed to use some buttermilk I'd bought with nothing particular in mind (again). It's surprising how many cakes there are which require buttermilk or soured cream when you have none in the fridge, but then they all disappear and hide when you have a pot of the aforementioned dairy products staring forlornly at you from the fridge, begging to be used up. Hence the creativity requirement.

I started out with the buttermilk birthday cake from How to be a Domestic Goddess (Nigella Lawson, obviously) and the baking tray I wanted to use required a four egg mix so I adapted. I wanted the chocolate portion to be orange flavoured, but the vanilla portion to remain plain. Here's what I came up with (please excuse the exact measurements, as I say, I scaled up a recipe, giving some bizarre amounts!):

Chocolate orange and vanilla marble cake
Ingredients
333g plain flour (or 300g plain + 33g self raising, if you run out of plain like me.....)
2 tsp baking powder
2/3tsp bicarbonate of soda
260ml buttermilk
2 tsp vanilla extract
166g softened butter
266g caster sugar
4 large eggs
30g cocoa powder
grated zest of 1 large orange

Method

- Preheat the oven to 180C/Gas 4. Grease and line an 8 x 12" cake tin.

- Sift the flour, baking powder and bicarb together into a bowl and set aside.

- Pour the buttermilk into a jug and stir in the vanilla.

- Cream the butter and sugar in a large bowl using an electric mixer until light and fluffy.

- Mixing slowly, add the eggs one at a time, continuing to mix for 30 seconds between each. Add a spoonful of flour if you're worried about the mixture splitting.

- Add flour mixture and buttermilk mixture alternately until all used up, blending well after each addition.

- When all thoroughly combined, pour approximately half the mixture into a smaller bowl and set aside.

- Sift the cocoa powder, remaining buttermilk from the carton (I used a 284ml carton so had a little left) and the zest of the orange to the remaining cake mix and combine until evenly brown coloured.

- Place blobs of mixture alternately into the tin and then, using the handle of a spoon (or something similar, a skewer is too thin for adequate mixing in my experience) drag back and forth through the mixture until you feel it is marbled. Don't do too much, you want to retain the individual colours and flavours. I was pleased with the way mine turned out (photo above and below).

- Bake for 50mins - 1 hour (but start checking at 40 mins if you know your oven is hot) until a skewer/cake tester comes out clean when inserted into the middle.

- Allow to cool for 10 minutes in the tin before unmoulding and allowing to cool completely on a wire rack.

I cut this into 18 generous pieces.

You can just see the marbled top of the cake. It has cracked slightly but no matter, you can see the dark and light mixtures peeking through.

This would definitely be my go-to cake recipe for a straightforward cake recipe from now on and it only requires buttermilk in addition to the normal sponge cake ingredients. It also takes adaptation very well!

This is a really, really delicious cake, it's moist (putting that down to the buttermilk) but light and tender at the same time, and was devoured at work. I was really pleased with the way the marbling worked and it didn't require any sort of icing or other embellishment. The chocolate orange flavour came through really well, although a stronger flavour other than vanilla would have been required to compete with it in the non-chocolate part - I might try lemon next time but it was gorgeous just as it was.