Chocolate Orange Marble Cake with Dark Chocolate Ganache

There are few flavour combinations as reliable as chocolate and orange and this chocolate orange marble cake takes that classic pairing and gives it a slightly more grown-up twist, with plenty of fresh orange zest, rich dark chocolate and a silky chocolate-orange ganache.

It’s still an easy cake to make, but the finished result feels a little more special than your everyday chocolate cake. The orange sponge is light and fragrant, while the chocolate layer is rich and fudgy, with little bursts of dark chocolate running through it.

You can serve it simply dusted with icing sugar, but if you’re making it for guests, I’d definitely go for the ganache. A little grated orange zest and some finely chopped dark chocolate on top makes it look far more complicated than it actually is.

And, as with most chocolate cakes, it never seems to last particularly long.

You will need

For the cake

• 250g unsalted butter, softened
• 250g caster sugar
• 250g self-raising flour
• 4 large eggs, at room temperature
• 2 large oranges
• 1 tsp vanilla extract
• 2 tbsp fresh orange juice
• 25g good-quality cocoa powder
• 1 tsp espresso powder, optional but highly recommended
• 75g dark chocolate, finely chopped
• 2 tbsp milk, if needed
• A small pinch of fine sea salt

For the chocolate-orange ganache

• 150g good-quality dark chocolate, around 60–70% cocoa solids
• 150ml double cream
• 1 tbsp unsalted butter
• 1 tsp finely grated orange zest
• 1 tsp fresh orange juice
• ½ tsp orange extract or a few drops of food-grade orange oil, optional

To finish

• Finely grated orange zest
• A little dark chocolate, finely grated or shaved
• Icing sugar, optional
• A small pinch of flaky sea salt, optional

Before you start

Preheat your oven to 180°C / 160°C fan / Gas Mark 4.

Grease a 20cm square cake tin or 900g loaf tin and line it with baking parchment, leaving a little overhang to make the cake easier to lift out.

Take your butter and eggs out of the fridge beforehand if you can. Room-temperature ingredients will give you a lighter, more evenly mixed cake.

How to make the cake

Start by finely grating the zest from both oranges. You want plenty of that fragrant orange zest because this is where a lot of the flavour comes from.

Put the softened butter and caster sugar into a large mixing bowl and beat for around 3–4 minutes, until the mixture is pale, light and fluffy. Don’t rush this stage – getting plenty of air into the butter and sugar helps give the cake a lovely texture.

Add the eggs one at a time, beating well between each addition. If the mixture looks like it’s beginning to curdle, don’t panic. A spoonful of the flour will bring it back together.

Add the vanilla, two tablespoons of fresh orange juice and most of the orange zest, keeping a little aside for decorating.

Sift in the self-raising flour and gently fold it through until you have a smooth batter. Try not to overmix at this stage.

Now for the chocolate part.

Spoon roughly one-third of the cake batter into a separate bowl. Add the cocoa powder, espresso powder if using, a small pinch of sea salt and the chopped dark chocolate. Fold everything together gently.

If the chocolate mixture feels noticeably thicker than the orange batter, add a tablespoon or two of milk to loosen it slightly.

Creating the marble effect

Spoon roughly half of the orange batter into your prepared tin.

Add the chocolate batter down the middle, then cover with the remaining orange batter.

You can leave the layers as they are for a more defined cake, or take a skewer or the handle of a teaspoon and gently swirl it through the mixture a few times.

Don’t go mad with the swirling. You want distinct ribbons of chocolate and orange rather than mixing everything together.

Bake

Place the cake in the centre of the oven and bake for approximately 40–50 minutes.

The exact cooking time will depend on the tin you’ve used.

The cake should be risen, golden and slightly springy when gently pressed in the centre. Insert a skewer into the middle – it should come out clean or with a few moist crumbs attached, but not wet cake batter.

If the top is browning too quickly, loosely cover it with a piece of foil for the final part of the cooking time.

Leave the cake in the tin for around 10 minutes, then lift it out onto a wire rack and allow it to cool completely before decorating.

Make the chocolate-orange ganache

Once the cake has cooled, make the ganache.

Finely chop the dark chocolate and place it in a heatproof bowl.

Warm the double cream in a small saucepan over a medium-low heat until it is hot and steaming but not boiling.

Pour the cream over the chocolate and leave it completely alone for around 3 minutes.

Then gently stir from the centre outwards until you have a smooth, glossy ganache.

Add the butter, orange zest and orange juice and stir until the butter has melted and everything is beautifully smooth.

If you’re using orange extract or food-grade orange oil, add it now. Go carefully – orange oil is powerful and you only need a tiny amount.

Leave the ganache for around 10–20 minutes until it has thickened enough to spread but is still lovely and glossy.

Decorate

Spoon the ganache over the cooled cake and gently spread it towards the edges, allowing a little to drip down the sides.

Finish with some finely grated orange zest and a scattering of dark chocolate shavings.

If you like the combination of sweet and salty, add just a tiny pinch of flaky sea salt over the top.

Alternatively, skip the ganache altogether and give the cooled cake a generous dusting of icing sugar.

It’s equally delicious.

A few tips for the best chocolate orange cake

Use fresh oranges. The zest makes a huge difference and gives you a much fresher flavour than orange flavouring alone.

Don’t skimp on the chocolate. A good dark chocolate gives the chocolate layer much more depth and stops the cake becoming overly sweet.

Don’t overmix the batter. Once the flour goes in, fold rather than aggressively beating it.

Don’t over-swirl. A few movements with a skewer are enough. You want those lovely chocolate and orange ribbons when you cut into the cake.

Let the cake cool completely before adding the ganache. Otherwise you’ll end up with a chocolate puddle rather than a beautifully glossy topping.

Can I make it without the ganache?

Absolutely.

The cake itself is delicious enough to serve on its own, particularly while it’s still slightly warm.

For a really simple finish, dust the top with icing sugar just before serving.

You could also serve individual slices with a little softly whipped cream and some finely grated orange zest.

For something slightly more indulgent, serve it with orange-infused crème fraîche or mascarpone.

Storing the cake

The un-iced cake will keep well in an airtight container for around 3–4 days.

Once you’ve added the ganache, keep it somewhere cool and consume within a few days.

Although realistically, if there’s chocolate cake sitting on the kitchen worktop, I wouldn’t expect it to make it that long.

The finished cake

What you end up with is a soft, buttery orange sponge with a rich chocolate centre, little pieces of dark chocolate throughout and a glossy chocolate-orange topping.

It’s familiar enough to feel comforting but just a little bit fancy.

Basically, your classic chocolate orange cake has put on a nice dress and gone out for dinner.

And nobody needs to know how easy it was to make.

We also have a gluten free version if you need to make this chocolate orange marble cake gluten and or dairy free